Eduardo Coelho

Measurements are presented of the Bs0→μ+μ− branching fraction and effective lifetime, as well as results of a search for the B0→μ+μ− decay in proton-proton collisions at s=13TeV at the LHC. The analysis is based on data collected with the CMS detector in 2016–2018 corresponding to an integrated luminosity of 140fb−1. The branching fraction of the Bs0→μ+μ− decay and the effective Bs0 meson lifetime are the most precise single measurements to date. No evidence for the B0→μ+μ− decay has been found. All results are found to be consistent with the standard model predictions and previous measurements.

At the start of Run 2 in 2015, the LHC delivered proton-proton collisions at a center-of-mass energy of 13 TeV. During Run 2 (years 2015-2018) the LHC eventually reached a luminosity of 2.1 $\times$ 10$^{34}$ cm$^{-2}$ s$^{-1}$, almost three times that reached during Run 1 (2009-2013) and a factor of two larger than the LHC design value, leading to events with up to a mean of about 50 simultaneous inelastic proton-proton collisions per bunch crossing (pileup). The CMS Level-1 trigger was upgraded prior to 2016 to improve the selection of physics events in the challenging conditions posed by the second run of the LHC. This paper describes the performance of the CMS Level-1 trigger upgrade during the data taking period of 2016-2018. The upgraded trigger implements pattern recognition and boosted decision tree regression techniques for muon reconstruction, includes pileup subtraction for jets and energy sums, and incorporates pileup-dependent isolation requirements for electrons and tau leptons. In addition, the new trigger calculates high-level quantities such as the invariant mass of pairs of reconstructed particles. The upgrade reduces the trigger rate from background processes and improves the trigger efficiency for a wide variety of physics signals.

A search for narrow and broad resonances with masses greater than 1.8 TeV decaying to a pair of jets is presented. The search uses proton-proton collision data at $\sqrt{s} =$ 13 TeV collected at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$. The background arising from standard model processes is predicted with the fit method used in previous publications and with a new method. The dijet invariant mass spectrum is well described by both data-driven methods, and no significant evidence for the production of new particles is observed. Model independent upper limits are reported on the production cross sections of narrow resonances, and broad resonances with widths up to 55% of the resonance mass. Limits are presented on the masses of narrow resonances from various models: string resonances, scalar diquarks, axigluons, colorons, excited quarks, color-octet scalars, W' and Z' bosons, Randall-Sundrum gravitons, and dark matter mediators. The limits on narrow resonances are improved by 200 to 800 GeV relative to those reported in previous CMS dijet resonance searches. The limits on dark matter mediators are presented as a function of the resonance mass and width, and on the associated coupling strength as a function of the mediator mass. These limits exclude at 95% confidence level a dark matter mediator with a mass of 1.8 TeV and width 1% of its mass or higher, up to one with a mass of 4.8 TeV and a width 45% of its mass or higher.

A measurement of the mass of the Higgs boson in the diphoton decay channel is presented. This analysis is based on 35.9 fb$^{-1}$ of proton-proton collision data collected during the 2016 LHC running period, with the CMS detector at a center-of-mass energy of 13 TeV. A refined detector calibration and new analysis techniques have been used to improve the precision of this measurement. The Higgs boson mass is measured to be $m_\mathrm{H} =$ 125.78 $\pm$ 0.26 GeV. This is combined with a measurement of $m_\mathrm{H}$ already performed in the H $\to$ ZZ $\to$ 4$\ell$ decay channel using the same data set, giving $m_\mathrm{H} =$ 125.46 $\pm$ 0.16 GeV. This result, when further combined with an earlier measurement of $m_\mathrm{H}$ using data collected in 2011 and 2012 with the CMS detector, gives a value for the Higgs boson mass of $m_\mathrm{H} =$ 125.38 $\pm$ 0.14 GeV. This is currently the most precise measurement of the mass of the Higgs boson.

Machine-learning (ML) techniques are explored to identify and classify hadronic decays of highly Lorentz-boosted W/Z/Higgs bosons and top quarks. Techniques without ML have also been evaluated and are included for comparison. The identification performances of a variety of algorithms are characterized in simulated events and directly compared with data. The algorithms are validated using proton-proton collision data at √s = 13TeV, corresponding to an integrated luminosity of 35.9 fb−1. Systematic uncertainties are assessed by comparing the results obtained using simulation and collision data. The new techniques studied in this paper provide significant performance improvements over non-ML techniques, reducing the background rate by up to an order of magnitude at the same signal efficiency.

A search is presented for a narrow resonance decaying to a pair of oppositely charged muons using $\sqrt{s}=13\text{ }\text{ }\mathrm{TeV}$ proton-proton collision data recorded at the LHC. In the 45--75 and 110--200 GeV resonance mass ranges, the search is based on conventional triggering and event reconstruction techniques. In the 11.5--45 GeV mass range, the search uses data collected with dimuon triggers with low transverse momentum thresholds, recorded at high rate by storing a reduced amount of trigger-level information. The data correspond to integrated luminosities of 137 and $96.6\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ for conventional and high-rate triggering, respectively. No significant resonant peaks are observed in the probed mass ranges. The search sets the most stringent constraints to date on a dark photon in the $\ensuremath{\sim}30--75$ and 110--200 GeV mass ranges.

With increasing instantaneous luminosity at the LHC come additional reconstruction challenges. At high luminosity, many collisions occur simultaneously within one proton-proton bunch crossing. The isolation of an interesting collision from the additional "pileup" collisions is needed for effective physics performance. In the CMS Collaboration, several techniques capable of mitigating the impact of these pileup collisions have been developed. Such methods include charged-hadron subtraction, pileup jet identification, isospin-based neutral particle "$\delta\beta$" correction, and, most recently, pileup per particle identification. This paper surveys the performance of these techniques for jet and missing transverse momentum reconstruction, as well as muon isolation. The analysis makes use of data corresponding to 35.9 fb$^{-1}$ collected with the CMS experiment in 2016 at a center-of-mass energy of 13 TeV. The performance of each algorithm is discussed for up to 70 simultaneous collisions per bunch crossing. Significant improvements are found in the identification of pileup jets, the jet energy, mass, and angular resolution, missing transverse momentum resolution, and muon isolation when using pileup per particle identification.

The first evidence for X(3872) production in relativistic heavy ion collisions is reported. The X(3872) production is studied in lead-lead (Pb-Pb) collisions at a center-of-mass energy of sNN=5.02 TeV per nucleon pair, using the decay chain X(3872)→J/ψπ+π−→μ+μ−π+π−. The data were recorded with the CMS detector in 2018 and correspond to an integrated luminosity of 1.7 nb−1. The measurement is performed in the rapidity and transverse momentum ranges |y|<1.6 and 15<pT<50 GeV/c. The significance of the inclusive X(3872) signal is 4.2 standard deviations. The prompt X(3872) to ψ2S yield ratio is found to be ρPb−Pb=1.08±0.49(stat)±0.52(syst), to be compared with typical values of 0.1 for pp collisions. This result provides a unique experimental input to theoretical models of the X(3872) production mechanism, and of the nature of this exotic state.Received 25 February 2021Revised 2 September 2021Accepted 22 December 2021DOI:https://doi.org/10.1103/PhysRevLett.128.032001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.© 2022 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Research AreasParticle & resonance productionQuark-gluon plasmaRelativistic heavy-ion collisionsTechniquesHadron collidersParticles & FieldsNuclear Physics

A bstract Three searches are presented for signatures of physics beyond the standard model (SM) in ττ final states in proton-proton collisions at the LHC, using a data sample collected with the CMS detector at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV, corresponding to an integrated luminosity of 138 fb − 1 . Upper limits at 95% confidence level (CL) are set on the products of the branching fraction for the decay into τ leptons and the cross sections for the production of a new boson ϕ , in addition to the H(125) boson, via gluon fusion (gg ϕ ) or in association with b quarks, ranging from $$ \mathcal{O} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>O</mml:mi> </mml:math> (10 pb) for a mass of 60 GeV to 0.3 fb for a mass of 3.5 TeV each. The data reveal two excesses for gg ϕ production with local p -values equivalent to about three standard deviations at m ϕ = 0 . 1 and 1.2 TeV. In a search for t -channel exchange of a vector leptoquark U 1 , 95% CL upper limits are set on the dimensionless U 1 leptoquark coupling to quarks and τ leptons ranging from 1 for a mass of 1 TeV to 6 for a mass of 5 TeV, depending on the scenario. In the interpretations of the $$ {M}_{\textrm{h}}^{125} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>M</mml:mi> <mml:mi>h</mml:mi> <mml:mn>125</mml:mn> </mml:msubsup> </mml:math> and $$ {M}_{\textrm{h},\textrm{EFT}}^{125} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>M</mml:mi> <mml:mrow> <mml:mi>h</mml:mi> <mml:mo>,</mml:mo> <mml:mi>EFT</mml:mi> </mml:mrow> <mml:mn>125</mml:mn> </mml:msubsup> </mml:math> minimal supersymmetric SM benchmark scenarios, additional Higgs bosons with masses below 350 GeV are excluded at 95% CL.

The first observation of the tt[over ¯]H process in a single Higgs boson decay channel with the full reconstruction of the final state (H→γγ) is presented, with a significance of 6.6 standard deviations (σ). The CP structure of Higgs boson couplings to fermions is measured, resulting in an exclusion of the pure CP-odd structure of the top Yukawa coupling at 3.2σ. The measurements are based on a sample of proton-proton collisions at a center-of-mass energy sqrt[s]=13 TeV collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb^{-1}. The cross section times branching fraction of the tt[over ¯]H process is measured to be σ_{tt[over ¯]H}B_{γγ}=1.56_{-0.32}^{+0.34} fb, which is compatible with the standard model prediction of 1.13_{-0.11}^{+0.08} fb. The fractional contribution of the CP-odd component is measured to be f_{CP}^{Htt}=0.00±0.33.

A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H→cc[over ¯], produced in association with a leptonically decaying V (W or Z) boson is presented. The search is performed with proton-proton collisions at sqrt[s]=13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb^{-1}. Novel charm jet identification and analysis methods using machine learning techniques are employed. The analysis is validated by searching for Z→cc[over ¯] in VZ events, leading to its first observation at a hadron collider with a significance of 5.7 standard deviations. The observed (expected) upper limit on σ(VH)B(H→cc[over ¯]) is 0.94 (0.50_{-0.15}^{+0.22})pb at 95% confidence level (C.L.), corresponding to 14 (7.6_{-2.3}^{+3.4}) times the standard model prediction. For the Higgs-charm Yukawa coupling modifier, κ_{c}, the observed (expected) 95% C.L. interval is 1.1<|κ_{c}|<5.5 (|κ_{c}|<3.4), the most stringent constraint to date.

A bstract The polarization of τ leptons is measured using leptonic and hadronic τ lepton decays in Z → τ + τ − events in proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb − 1 . The measured τ − lepton polarization at the Z boson mass pole is $$ {\mathcal{P}}_{\tau}\left(\textrm{Z}\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>P</mml:mi> <mml:mi>τ</mml:mi> </mml:msub> <mml:mfenced> <mml:mi>Z</mml:mi> </mml:mfenced> </mml:math> = −0.144 ± 0.006 (stat) ± 0.014 (syst) = −0.144 ± 0.015, in good agreement with the measurement of the τ lepton asymmetry parameter of A τ = 0.1439 ± 0.0043 = $$ -{\mathcal{P}}_{\tau}\left(\textrm{Z}\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>−</mml:mo> <mml:msub> <mml:mi>P</mml:mi> <mml:mi>τ</mml:mi> </mml:msub> <mml:mfenced> <mml:mi>Z</mml:mi> </mml:mfenced> </mml:math> at LEP. The τ lepton polarization depends on the ratio of the vector to axial-vector couplings of the τ leptons in the neutral current expression, and thus on the effective weak mixing angle sin 2 $$ {\theta}_{\textrm{W}}^{\textrm{eff}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>θ</mml:mi> <mml:mi>W</mml:mi> <mml:mi>eff</mml:mi> </mml:msubsup> </mml:math> , independently of the Z boson production mechanism. The obtained value sin 2 $$ {\theta}_{\textrm{W}}^{\textrm{eff}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>θ</mml:mi> <mml:mi>W</mml:mi> <mml:mi>eff</mml:mi> </mml:msubsup> </mml:math> = 0.2319 ± 0 . 0008(stat) ± 0 . 0018(syst) = 0 . 2319 ± 0 . 0019 is in good agreement with measurements at e + e − colliders.

A bstract The production of prompt $$ {\Lambda}_{\textrm{c}}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> baryons is measured via the exclusive decay channel $$ {\Lambda}_{\textrm{c}}^{+}\to p{\textrm{K}}^{-}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:mi>p</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> at a center-of-mass energy per nucleon pair of 5.02 TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb − 1 , respectively. The measurements are performed within the $$ {\Lambda}_{\textrm{c}}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> rapidity interval | y | &lt; 1 with transverse momentum ( p T ) ranges of 3–30 and 6–40 GeV/ c for pp and PbPb collisions, respectively. Compared to the yields in pp collisions scaled by the expected number of nucleon-nucleon interactions, the observed yields of $$ {\Lambda}_{\textrm{c}}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> with p T &gt; 10 GeV/ c are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The $$ {\Lambda}_{\textrm{c}}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> / D 0 production ratio is similar in PbPb and pp collisions at p T &gt; 10 GeV/ c , suggesting that the coalescence process does not play a dominant role in prompt $$ {\Lambda}_{\textrm{c}}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> baryon production at higher p T .

The first search for scalar leptoquarks produced in τ-lepton–quark collisions is presented. It is based on a set of proton-proton collision data recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb−1. The reconstructed final state consists of a jet, significant missing transverse momentum, and a τ lepton reconstructed through its hadronic or leptonic decays. Limits are set on the product of the leptoquark production cross section and branching fraction and interpreted as exclusions in the plane of the leptoquark mass and the leptoquark-τ-quark coupling strength.Received 11 August 2023Accepted 19 December 2023DOI:https://doi.org/10.1103/PhysRevLett.132.061801Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.© 2024 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Physical SystemsLeptoquarksTau leptonsTechniquesHadron collidersParticles & Fields

A search is reported for near-threshold structures in the J/ψJ/ψ invariant mass spectrum produced in proton-proton collisions at sqrt[s]=13 TeV from data collected by the CMS experiment, corresponding to an integrated luminosity of 135 fb^{-1}. Three structures are found, and a model with quantum interference among these structures provides a good description of the data. A new structure is observed with a local significance above 5 standard deviations at a mass of 6638_{-38}^{+43}(stat)_{-31}^{+16}(syst) MeV. Another structure with even higher significance is found at a mass of 6847_{-28}^{+44}(stat)_{-20}^{+48}(syst) MeV, which is consistent with the X(6900) resonance reported by the LHCb experiment and confirmed by the ATLAS experiment. Evidence for another new structure, with a local significance of 4.7 standard deviations, is found at a mass of 7134_{-25}^{+48}(stat)_{-15}^{+41}(syst) MeV. Results are also reported for a model without interference, which does not fit the data as well and shows mass shifts up to 150 MeV relative to the model with interference.

The observation of WWγ production in proton-proton collisions at a center-of-mass energy of 13 TeV with an integrated luminosity of 138 fb^{-1} is presented. The observed (expected) significance is 5.6 (5.1) standard deviations. Events are selected by requiring exactly two leptons (one electron and one muon) of opposite charge, moderate missing transverse momentum, and a photon. The measured fiducial cross section for WWγ is 5.9±0.8(stat)±0.8(syst)±0.7(modeling) fb, in agreement with the next-to-leading order quantum chromodynamics prediction. The analysis is extended with a search for the associated production of the Higgs boson and a photon, which is generated by a coupling of the Higgs boson to light quarks. The result is used to constrain the Higgs boson couplings to light quarks.

A tagging algorithm to identify jets that are significantly displaced from the proton-proton (pp) collision region in the CMS detector at the LHC is presented. Displaced jets can arise from the decays of long-lived particles (LLPs), which are predicted by several theoretical extensions of the standard model. The tagger is a multiclass classifier based on a deep neural network, which is parameterised according to the proper decay length $\mathrm{c}\tau_0$ of the LLP. A novel scheme is defined to reliably label jets from LLP decays for supervised learning. Samples of pp collision data, recorded by the CMS detector at a centre-of-mass energy of 13 TeV, and simulated events are used to train the neural network. Domain adaptation by backward propagation is performed to improve the simulation modelling of the jet class probability distributions observed in pp collision data. The potential performance of the tagger is demonstrated with a search for long-lived gluinos, a manifestation of split supersymmetric models. The tagger provides a rejection factor of 10 000 for jets from standard model processes, while maintaining an LLP jet tagging efficiency of 30-80% for gluinos with 1 mm $\leq$ $c\tau_0$ $\leq$ 10 m. The expected coverage of the parameter space for split supersymmetry is presented.

Measurement of the fiducial inclusive and differential production cross sections of the Higgs boson in proton-proton collisions at $\sqrt{s} =$ 13 TeV are performed using events where the Higgs boson decays into a pair of W bosons that subsequently decay into a final state with an electron, a muon, and a pair of neutrinos. The analysis is based on data collected with the CMS detector at the LHC during 2016-2018, corresponding to an integrated luminosity of 137 fb$^{-1}$. Production cross sections are measured as a function of the transverse momentum of the Higgs boson and the associated jet multiplicity. The Higgs boson signal is extracted and simultaneously unfolded to correct for selection efficiency and resolution effects using maximum-likelihood fits to the observed distributions in data. The integrated fiducial cross section is measured to be 86.5 $\pm$ 9.5 fb, consistent with the Standard Model expectation of 82.5 $\pm$ 4.2 fb. No significant deviation from the Standard Model expectations is observed in the differential measurements.

Measurements of the second Fourier harmonic coefficient ($v_2$) of the azimuthal distributions of prompt and nonprompt D$^0$ mesons produced in pp and pPb collisions are presented. Nonprompt D$^0$ mesons come from beauty hadron decays. The data samples are collected by the CMS experiment at nucleon-nucleon center-of-mass energies of 13 and 8.16 TeV, respectively. In high multiplicity pp collisions, $v_2$ signals for prompt charm hadrons are reported for the first time, and are found to be comparable to those for light-flavor hadron species over a transverse momentum ($p_\mathrm{T}$) range of 2-6 GeV. Compared at similar event multiplicities, the prompt D$^0$ meson $v_2$ values in pp and pPb collisions are similar in magnitude. The $v_2$ values for open beauty hadrons are extracted for the first time via nonprompt D$^0$ mesons in pPb collisions. For $p_\mathrm{T}$ in the range of 2-5 GeV, the results suggest that $v_2$ for nonprompt D$^0$ mesons are smaller than those for prompt D$^0$ mesons. These new measurements indicate a positive charm hadron $v_2$ in pp collisions and suggest a mass dependence in $v_2$ between charm and beauty hadrons in the pPb system. These results provide insights into the origin of heavy-flavor quark collectivity in small systems.

An inclusive search for long-lived exotic particles decaying to a pair of muons is presented. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV in 2016 and 2018 and corresponding to an integrated luminosity of 97.6 fb$^{-1}$. The experimental signature is a pair of oppositely charged muons originating from a common secondary vertex spatially separated from the pp interaction point by distances ranging from several hundred $\mu$m to several meters. The results are interpreted in the frameworks of the hidden Abelian Higgs model, in which the Higgs boson decays to a pair of long-lived dark photons Z$_\mathrm{D}$, and of a simplified model, in which long-lived particles are produced in decays of an exotic heavy neutral scalar boson. For the hidden Abelian Higgs model with $m_\mathrm{Z_D}$ greater than 20 GeV and less than half the mass of the Higgs boson, they provide the best limits to date on the branching fraction of the Higgs boson to dark photons for $c\tau$(Z$_\mathrm{D}$) (varying with $m_\mathrm{Z_D}$) between 0.03 and ${\approx}$ 0.5 mm, and above ${\approx}$ 0.5 m. Our results also yield the best constraints on long-lived particles with masses larger than 10 GeV produced in decays of an exotic scalar boson heavier than the Higgs boson and decaying to a pair of muons.

A bstract A search is presented for vector-like T and B quark-antiquark pairs produced in proton-proton collisions at a center-of-mass energy of 13 TeV. Data were collected by the CMS experiment at the CERN LHC in 2016–2018, with an integrated luminosity of 138 fb − 1 . Events are separated into single-lepton, same-sign charge dilepton, and multi-lepton channels. In the analysis of the single-lepton channel a multilayer neural network and jet identification techniques are employed to select signal events, while the same-sign dilepton and multilepton channels rely on the high-energy signature of the signal to distinguish it from standard model backgrounds. The data are consistent with standard model background predictions, and the production of vector-like quark pairs is excluded at 95% confidence level for T quark masses up to 1.54 TeV and B quark masses up to 1.56 TeV, depending on the branching fractions assumed, with maximal sensitivity to decay modes that include multiple top quarks. The limits obtained in this search are the strongest limits to date for $$ \textrm{T}\overline{\textrm{T}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>T</mml:mi> <mml:mover> <mml:mi>T</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> production, excluding masses below 1.48 TeV for all decays to third generation quarks, and are the strongest limits to date for $$ \textrm{B}\overline{\textrm{B}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> production with B quark decays to tW.

A search for the lepton-flavor violating decay of the Higgs boson and potential additional Higgs bosons with a mass in the range 110--160 GeV to an ${e}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}$ pair is presented. The search is performed with a proton-proton collision dataset at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of $138\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. No excess is observed for the Higgs boson. The observed (expected) upper limit on the ${e}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}$ branching fraction for it is determined to be $4.4(4.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at 95% confidence level, the most stringent limit set thus far from direct searches. The largest excess of events over the expected background in the full mass range of the search is observed at an ${e}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ensuremath{\mp}}$ invariant mass of approximately 146 GeV with a local (global) significance of 3.8 (2.8) standard deviations.

Abstract A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at $${\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mspace /> <mml:mtext>Te</mml:mtext> <mml:mspace /> <mml:mtext>V</mml:mtext> </mml:mrow> </mml:math> by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:msup> <mml:mtext>fb</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . The 95% confidence level upper limit set on the branching fraction of the 125 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:mtext>Ge</mml:mtext> <mml:mspace /> <mml:mtext>V</mml:mtext> </mml:mrow> </mml:math> Higgs boson to invisible particles, $${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>B</mml:mi> <mml:mo>(</mml:mo> <mml:mtext>H</mml:mtext> <mml:mo>→</mml:mo> <mml:mtext>inv</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> , is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous $${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>B</mml:mi> <mml:mo>(</mml:mo> <mml:mtext>H</mml:mtext> <mml:mo>→</mml:mo> <mml:mtext>inv</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> searches carried out at $${\sqrt{s}=7}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>7</mml:mn> </mml:mrow> </mml:math> , 8, and 13 $$\,\text {Te}\hspace{-.08em}\text {V}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:mtext>Te</mml:mtext> <mml:mspace /> <mml:mtext>V</mml:mtext> </mml:mrow> </mml:math> in complementary production modes. The combined upper limit at 95% confidence level on $${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>B</mml:mi> <mml:mo>(</mml:mo> <mml:mtext>H</mml:mtext> <mml:mo>→</mml:mo> <mml:mtext>inv</mml:mtext> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> is 0.15 (0.08 expected).

The observation of the production of four top quarks in proton-proton collisions is reported, based on a data sample collected by the CMS experiment at a center-of-mass energy of 13 TeV in 2016–2018 at the CERN LHC and corresponding to an integrated luminosity of 138fb−1. Events with two same-sign, three, or four charged leptons (electrons and muons) and additional jets are analyzed. Compared to previous results in these channels, updated identification techniques for charged leptons and jets originating from the hadronization of b quarks, as well as a revised multivariate analysis strategy to distinguish the signal process from the main backgrounds, lead to an improved expected signal significance of 4.9 standard deviations above the background-only hypothesis. Four top quark production is observed with a significance of 5.6 standard deviations, and its cross section is measured to be 17.7−3.5+3.7(stat)−1.9+2.3(syst)fb, in agreement with the available standard model predictions.

A bstract A search for physics beyond the standard model in events with at least three charged leptons (electrons or muons) is presented. The data sample corresponds to an integrated luminosity of 137 fb − 1 of proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV, collected with the CMS detector at the LHC in 2016–2018. The two targeted signal processes are pair production of type-III seesaw heavy fermions and production of a light scalar or pseudoscalar boson in association with a pair of top quarks. The heavy fermions may be manifested as an excess of events with large values of leptonic transverse momenta or missing transverse momentum. The light scalars or pseudoscalars may create a localized excess in the dilepton mass spectra. The results exclude heavy fermions of the type-III seesaw model for masses below 880 GeV at 95% confidence level in the scenario of equal branching fractions to each lepton flavor. This is the most restrictive limit on the flavor-democratic scenario of the type-III seesaw model to date. Assuming a Yukawa coupling of unit strength to top quarks, branching fractions of new scalar (pseudoscalar) bosons to dielectrons or dimuons above 0.004 (0.03) and 0.04 (0.03) are excluded at 95% confidence level for masses in the range 15–75 and 108–340 GeV, respectively. These are the first limits in these channels on an extension of the standard model with scalar or pseudoscalar particles.

The second-order Fourier coefficients ($v_2$) characterizing the azimuthal distribution of $\Upsilon$(1S) and $\Upsilon$(2S) mesons arising from PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV are studied. The $\Upsilon$ mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The data set corresponds to an integrated luminosity of 1.7 nb$^{-1}$. The scalar product method is used to extract the $v_2$ coefficients of the azimuthal distribution. Results are reported for the rapidity range $|y|$ $\lt$ 2.4, with the transverse momentum 0 $\lt$ $p_\mathrm{T}$ $\lt$ 50 GeV/$c$, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/$\psi$ mesons, the measured $v_2$ values for the $\Upsilon$ mesons are found to be consistent with zero.

The results of a search for Higgs boson pair (HH) production in the WW*WW*, WW*$\tau\tau$, and $\tau\tau\tau\tau$ decay modes are presented. The search uses 138 fb$^{-1}$ of proton-proton collision data recorded by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV from 2016 to 2018. Analyzed events contain two, three, or four reconstructed leptons, including electrons, muons, and hadronically decaying tau leptons. No evidence for a signal is found in the data. Upper limits are set on the cross section for nonresonant HH production, as well as resonant production in which a new heavy particle decays to a pair of Higgs bosons. For nonresonant production, the observed (expected) upper limit on the cross section at 95% confidence level (CL) is 21.3 (19.4) times the standard model (SM) prediction. The observed (expected) ratio of the trilinear Higgs boson self-coupling to its value in the SM is constrained to be within the interval $-$6.9 to 11.1 ($-$6.9 to 11.7) at 95% CL, and limits are set on a variety of new-physics models using an effective field theory approach. The observed (expected) limits on the cross section for resonant HH production range from 0.18 to 0.90 (0.08 to 1.06) pb at 95% CL for new heavy-particle masses in the range 250-1000 GeV.

A search for pairs of dijet resonances with the same mass is conducted in final states with at least four jets. Results are presented separately for the case where the four jet production proceeds via an intermediate resonant state and for nonresonant production. The search uses a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$ collected by the CMS detector in proton-proton collisions at $\sqrt{s}$ = 13 TeV. Model-independent limits, at 95% confidence level, are reported on the production cross section of four-jet and dijet resonances. These first LHC limits on resonant pair production of dijet resonances via high mass intermediate states are applied to a signal model of diquarks that decay into pairs of vector-like quarks, excluding diquark masses below 7.6 TeV for a particular model scenario. There are two events in the tails of the distributions, each with a four-jet mass of 8 TeV and an average dijet mass of 2 TeV, resulting in local and global significances of 3.9 and 1.6 standard deviations, respectively, if interpreted as a signal. The nonresonant search excludes pair production of top squarks with masses between 0.50 TeV to 0.77 TeV, with the exception of a small interval between 0.52 and 0.58 TeV, for supersymmetric $R$-parity-violating decays to quark pairs, significantly extending previous limits. Here, the most significant excess above the predicted background occurs at an average dijet mass of 0.95 TeV, for which the local and global significances are 3.6 and 2.5 standard deviations, respectively.

The production of a top quark-antiquark pair in association with a W boson ($\mathrm{t\bar{t}}$W) is measured in proton-proton collisions at a center-of-mass energy of 13 TeV. The analyzed data was recorded by the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 138 fb$^{-1}$. Events with two or three leptons (electrons and muons) and additional jets are selected. In events with two leptons, a multiclass neural network is used to distinguish between the signal and background processes. Events with three leptons are categorized based on the number of jets and of jets originating from b quark hadronization, and the lepton charges. The inclusive $\mathrm{t\bar{t}}$W production cross section in the full phase space is measured to be 868 $\pm$ 40 (stat) $\pm$ 51 (syst) fb. The $\mathrm{t\bar{t}}$W$^+$ and $\mathrm{t\bar{t}}$W$^-$ cross sections are also measured as 553 $\pm$ 30 (stat) $\pm$ 30 (syst) and 343 $\pm$ 26 (stat) $\pm$ 25 (syst) fb, respectively, and the corresponding ratio of the two cross sections is found to be 1.61 $\pm$ 0.15 (stat) $^{+0.07}_{-0.05}$ (syst). The measured cross sections are larger than but consistent with the standard model predictions within two standard deviations, and represent the most precise measurement of these cross sections to date.

Jet production in lead-lead (PbPb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is studied with the CMS detector at the LHC, using PbPb and pp data samples corresponding to integrated luminosities of 404 $\mu$b$^{-1}$ and 27.4 pb$^{-1}$, respectively. Jets with different areas are reconstructed using the anti-$k_\mathrm{T}$ algorithm by varying the distance parameter $R$. The measurements are performed using jets with transverse momenta ($p_\mathrm{T}$) greater than 200 GeV and in a pseudorapidity range of $|\eta|$ $\lt$ 2. To reveal the medium modification of the jet spectra in PbPb collisions, the properly normalized ratio of spectra from PbPb and pp data is used to extract jet nuclear modification factors as functions of the PbPb collision centrality, $p_\mathrm{T}$ and, for the first time, as a function of $R$ up to 1.0. For the most central collisions, a strong suppression is observed for high-$p_\mathrm{T}$ jets reconstructed with all distance parameters, implying that a significant amount of jet energy is scattered to large angles. The dependence of jet suppression on $R$ is expected to be sensitive to both the jet energy loss mechanism and the medium response, and so the data are compared to several modern event generators and analytic calculations. The models considered do not fully reproduce the data.

Abstract We describe a method to obtain point and dispersion estimates for the energies of jets arising from b quarks produced in proton–proton collisions at an energy of $$\sqrt{s}=13\,\text {TeV} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mspace /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math> at the CERN LHC. The algorithm is trained on a large sample of simulated b jets and validated on data recorded by the CMS detector in 2017 corresponding to an integrated luminosity of 41 $$\,\text {fb}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mspace /><mml:msup><mml:mtext>fb</mml:mtext><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> . A multivariate regression algorithm based on a deep feed-forward neural network employs jet composition and shape information, and the properties of reconstructed secondary vertices associated with the jet. The results of the algorithm are used to improve the sensitivity of analyses that make use of b jets in the final state, such as the observation of Higgs boson decay to $$\hbox {b}\bar{\hbox {b}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mtext>b</mml:mtext><mml:mover><mml:mrow><mml:mtext>b</mml:mtext></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:mrow></mml:math> .

Production cross sections of $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) states decaying into \muplusmuminus in proton-lead (pPb) collisions are reported using data collected by the CMS experiment at$\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. A comparison is made with corresponding cross sections obtained with pp data measured at the same collision energy and scaled by the Pb nucleus mass number. The nuclear modification factor for $\Upsilon$(1S) is found to be $R_\mathrm{pPb}(\Upsilon(1S))$ = 0.806 $\pm$ 0.024 (stat) $\pm$ 0.059 (syst). Similar results for the excited states indicate a sequential suppression pattern, such that $R_\mathrm{pPb}(\Upsilon(1S)) \gt R_\mathrm{pPb}(\Upsilon(2S)) \gt R_\mathrm{pPb}(\Upsilon(3S))$. The suppression is much less pronounced in pPb than in PbPb collisions, and independent of transverse momentum $p_\mathrm{T}^\Upsilon$ and center-of-mass rapidity $y_\mathrm{CM}^\Upsilon$ of the individual $\Upsilon$ state in the studied range $p_\mathrm{T}^\Upsilon \lt $ 30 GeV$/c$ and $\vert y_\mathrm{CM}^\Upsilon\vert \lt$ 1.93. Models that incorporate sequential suppression of bottomonia in pPb collisions are in better agreement with the data than those which only assume initial-state modifications.

The first search exploiting the vector boson fusion process to probe heavy Majorana neutrinos and the Weinberg operator at the LHC is presented. The search is performed in the same-sign dimuon final state using a proton-proton collision dataset recorded at sqrt[s]=13 TeV, collected with the CMS detector and corresponding to a total integrated luminosity of 138 fb^{-1}. The results are found to agree with the predictions of the standard model. For heavy Majorana neutrinos, constraints on the squared mixing element between the muon and the heavy neutrino are derived in the heavy neutrino mass range 50 GeV-25 TeV; for masses above 650 GeV these are the most stringent constraints from searches at the LHC to date. A first test of the Weinberg operator at colliders provides an observed upper limit at 95% confidence level on the effective μμ Majorana neutrino mass of 10.8 GeV.

A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138 fb^{-1} collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, κ_{2V}, excluding κ_{2V}=0 for the first time, with a significance of 6.3 standard deviations when other H couplings are fixed to their standard model values.

A bstract A search for a charged Higgs boson H ± decaying into a heavy neutral Higgs boson H and a W boson is presented. The analysis targets the H decay into a pair of tau leptons with at least one of them decaying hadronically and with an additional electron or muon present in the event. The search is based on proton-proton collision data recorded by the CMS experiment during 2016–2018 at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV, corresponding to an integrated luminosity of 138 fb − 1 . The data are consistent with standard model background expectations. Upper limits at 95% confidence level are set on the product of the cross section and branching fraction for an H ± in the mass range of 300–700 GeV, assuming an H with a mass of 200 GeV. The observed limits range from 0.085 pb for an H ± mass of 300 Ge V to 0.019 pb for a mass of 700 GeV. These are the first limits on H ± production in the H ± → HW ± decay channel at the LHC.

A bstract A search for physics beyond the standard model (SM) in the final state with a hadronically decaying tau lepton and a neutrino is presented. This analysis is based on data recorded by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to a total integrated luminosity of 138 fb − 1 . The transverse mass spectrum is analyzed for the presence of new physics. No significant deviation from the SM prediction is observed. Limits are set on the production cross section of a W′ boson decaying into a tau lepton and a neutrino. Lower limits are set on the mass of the sequential SM-like heavy charged vector boson and the mass of a quantum black hole. Upper limits are placed on the couplings of a new boson to the SM fermions. Constraints are put on a nonuniversal gauge interaction model and an effective field theory model. For the first time, upper limits on the cross section of t -channel leptoquark (LQ) exchange are presented. These limits are translated into exclusion limits on the LQ mass and on its coupling in the t -channel. The sensitivity of this analysis extends into the parameter space of LQ models that attempt to explain the anomalies observed in B meson decays. The limits presented for the various interpretations are the most stringent to date. Additionally, a model-independent limit is provided.

A data sample of events from proton-proton collisions with at least two jets, and two isolated same-sign or three or more charged leptons, is studied in a search for signatures of new physics phenomena. The data correspond to an integrated luminosity of 137fb-1 at a center-of-mass energy of 13TeV , collected in 2016-2018 by the CMS experiment at the LHC. The search is performed using a total of 168 signal regions defined using several kinematic variables. The properties of the events are found to be consistent with the expectations from standard model processes. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos or squarks for various decay scenarios in the context of supersymmetric models conserving or violating R parity. The observed lower mass limits are as large as 2.1TeV for gluinos and 0.9TeV for top and bottom squarks. To facilitate reinterpretations, model-independent limits are provided in a set of simplified signal regions.

A bstract The momentum-weighted sum of the electric charges of particles inside a jet, known as jet charge, is sensitive to the electric charge of the particle initiating the parton shower. This paper presents jet charge distributions in $$ \sqrt{s_{\mathrm{NN}}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math> = 5 . 02 TeV lead-lead (PbPb) and proton-proton (pp) collisions recorded with the CMS detector at the LHC. These data correspond to integrated luminosities of 404 μ b − 1 and 27.4 pb − 1 for PbPb and pp collisions, respectively. Leveraging the sensitivity of the jet charge to fundamental differences in the electric charges of quarks and gluons, the jet charge distributions from simulated events are used as templates to extract the quark- and gluon-like jet fractions from data. The modification of these jet fractions is examined by comparing pp and PbPb data as a function of the overlap of the colliding Pb nuclei (centrality). This measurement tests the color charge dependence of jet energy loss due to interactions with the quark-gluon plasma. No significant modification between different centrality classes and with respect to pp results is observed in the extracted quark- and gluon-like jet fractions.

A bstract The ratios of the production cross sections between the excited ϒ(2S) and ϒ(3S) mesons and the ϒ(1S) ground state, detected via their decay into two muons, are studied as a function of the number of charged particles in the event. The data are from proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 7 TeV, corresponding to an integrated luminosity of 4.8 fb − 1 , collected with the CMS detector at the LHC. Evidence of a decrease in these ratios as a function of the particle multiplicity is observed, more pronounced at low transverse momentum $$ {p}_{\mathrm{T}}^{\upmu \upmu} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>μμ</mml:mi> </mml:msubsup> </mml:math> . For ϒ(nS) mesons with $$ {p}_{\mathrm{T}}^{\upmu \upmu} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>μμ</mml:mi> </mml:msubsup> </mml:math> &gt; 7 GeV, where most of the data were collected, the correlation with multiplicity is studied as a function of the underlying event transverse sphericity and the number of particles in a cone around the ϒ(nS) direction. The ratios are found to be multiplicity independent for jet-like events. The mean $$ {p}_{\mathrm{T}}^{\upmu \upmu} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>μμ</mml:mi> </mml:msubsup> </mml:math> values for the ϒ(nS) states as a function of particle multiplicity are also measured and found to grow more steeply as their mass increases.

The first evidence for X(3872) production in relativistic heavy ion collisions is reported. The X(3872) production is studied in lead-lead (PbPb) collisions at a center-of-mass energy of $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV per nucleon pair, using the decay chain X(3872) $\to$ J$/ψ\, π^+π^- \to$ $μ^+μ^-π^+π^-$. The data were recorded with the CMS detector in 2018 and correspond to an integrated luminosity of 1.7 nb$^{-1}$. The measurement is performed in the rapidity and transverse momentum ranges $|y|$ $\lt$ 1.6 and 15 $\lt$ $p_\mathrm{T}$ $\lt$ 50 GeV$/c$. The significance of the inclusive X(3872) signal is 4.2 standard deviations. The prompt X(3872) to $ψ$(2S) yield ratio is found to be $ρ^\mathrm{PbPb} = $ 1.08 $\pm$ 0.49 (stat) $\pm$ 0.52 (syst), to be compared with typical values of 0.1 for pp collisions. This result provides a unique experimental input to theoretical models of the X(3872) production mechanism, and of the nature of this exotic state.

A search for the pair production of the lightest supersymmetric partner of the top quark, the top squark ($\tilde{\mathrm{t}}_1$), is presented. The search targets the four-body decay of the $\tilde{\mathrm{t}}_1$, which is preferred when the mass difference between the top squark and the lightest supersymmetric particle is smaller than the mass of the W boson. This decay mode consists of a bottom quark, two other fermions, and the lightest neutralino ($\tilde{\chi}^0_1$), which is assumed to be the lightest supersymmetric particle. The data correspond to an integrated luminosity of 138 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC. Events are selected using the presence of a high-momentum jet, an electron or muon with low transverse momentum, and a significant missing transverse momentum. The signal is selected based on a multivariate approach that is optimized for the difference between $m(\tilde{\mathrm{t}}_1)$ and $m(\tilde{\chi}^0_1)$. The contribution from leading background processes is estimated from data. No significant excess is observed above the expectation from standard model processes. The results of this search exclude top squarks at 95% confidence level for masses up to 480 and 700 GeV for $m(\tilde{\mathrm{t}}_1) - m(\tilde{\chi}^0_1$) = 10 and 80 GeV, respectively.

Abstract A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production ( $$\hbox {t}\overline{\hbox {t}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>t</mml:mtext> <mml:mover> <mml:mtext>t</mml:mtext> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> </mml:math> ) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:mtext>Ge</mml:mtext> <mml:mspace /> <mml:mtext>V</mml:mtext> </mml:mrow> </mml:math> . The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace /> <mml:msup> <mml:mtext>fb</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . The differential $$\hbox {t}\overline{\hbox {t}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>t</mml:mtext> <mml:mover> <mml:mtext>t</mml:mtext> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> </mml:math> production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of $$173.06 \pm 0.84\,\text {Ge}\hspace{-.08em}\text {V} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>173.06</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.84</mml:mn> <mml:mspace /> <mml:mtext>Ge</mml:mtext> <mml:mspace /> <mml:mtext>V</mml:mtext> </mml:mrow> </mml:math> .

A search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZH boson pairs in the all-jets final state is presented. The analysis is based on proton-proton collision data recorded by the CMS detector in 2016–2018 at a centre-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 138 fb−1. The search is sensitive to resonances with masses between 1.3 and 6TeV, decaying to bosons that are highly Lorentz-boosted such that each of the bosons forms a single large-radius jet. Machine learning techniques are employed to identify such jets. No significant excess over the estimated standard model background is observed. A maximum local significance of 3.6 standard deviations, corresponding to a global significance of 2.3 standard deviations, is observed at masses of 2.1 and 2.9 TeV. In a heavy vector triplet model, spin-1 Z′ and W′ resonances with masses below 4.8TeV are excluded at the 95% confidence level (CL). These limits are the most stringent to date. In a bulk graviton model, spin-2 gravitons and spin-0 radions with masses below 1.4 and 2.7TeV, respectively, are excluded at 95% CL. Production of heavy resonances through vector boson fusion is constrained with upper cross section limits at 95% CL as low as 0.1 fb.

The first study of the shapes of jets arising from bottom (b) quarks in heavy ion collisions is presented. Jet shapes are studied using charged hadron constituents as a function of their radial distance from the jet axis. Lead-lead (PbPb) collision data at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV were recorded by the CMS detector at the LHC, with an integrated luminosity of 1.69 nb$^{-1}$. Compared to proton-proton collisions, a redistribution of the energy in b jets to larger distances from the jet axis is observed in PbPb collisions. This medium-induced redistribution is found to be substantially larger for b jets than for inclusive jets.

A bstract Measurements of the inclusive and normalised differential cross sections are presented for the production of single top quarks in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data used were recorded with the CMS detector at the LHC during 2016–2018, and correspond to an integrated luminosity of 138 fb − 1 . Events containing one electron and one muon in the final state are analysed. For the inclusive measurement, a multivariate discriminant, exploiting the kinematic properties of the events is used to separate the signal from the dominant $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> background. A cross section of $$ 79.2\pm 0.9{\left(\textrm{stat}\right)}_{-8.0}^{+7.7}\left(\textrm{syst}\right)\pm 1.2\left(\textrm{lumi}\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>79.2</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.9</mml:mn> <mml:msubsup> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>8.0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>7.7</mml:mn> </mml:mrow> </mml:msubsup> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>1.2</mml:mn> <mml:mfenced> <mml:mtext>lumi</mml:mtext> </mml:mfenced> </mml:math> pb is obtained, consistent with the predictions of the standard model. For the differential measurements, a fiducial region is defined according to the detector acceptance, and the requirement of exactly one jet coming from the fragmentation of a bottom quark. The resulting distributions are unfolded to particle level and agree with the predictions at next-to-leading order in perturbative quantum chromodynamics.

A bstract The measurements of the inclusive and differential fiducial cross sections of the Higgs boson decaying to a pair of photons are presented. The analysis is performed using proton-proton collisions data recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 137 fb − 1 . The inclusive fiducial cross section is measured to be $$ {\sigma}_{\textrm{fid}}={73.4}_{-5.3}^{+5.4}{\left(\textrm{stat}\right)}_{-2.2}^{+2.4}\left(\textrm{syst}\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>σ</mml:mi> <mml:mi>fid</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mn>73.4</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5.3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>5.4</mml:mn> </mml:mrow> </mml:msubsup> <mml:msubsup> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.4</mml:mn> </mml:mrow> </mml:msubsup> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> </mml:math> fb, in agreement with the standard model expectation of 75 . 4 ± 4 . 1 fb. The measurements are also performed in fiducial regions targeting different production modes and as function of several observables describing the diphoton system, the number of additional jets present in the event, and other kinematic observables. Two double differential measurements are performed. No significant deviations from the standard model expectations are observed.

The production of four top quarks ($\mathrm{t\bar{t}t\bar{t}}$) is studied with LHC proton-proton collision data samples collected by the CMS experiment at a center-of-mass energy of 13 TeV, and corresponding to integrated luminosities of up to 138 fb$^{-1}$. Events that have no leptons (all-hadronic), one lepton, or two opposite-sign leptons (where lepton refers only to prompt electrons or prompt muons) are considered. This is the first $\mathrm{t\bar{t}t\bar{t}}$ measurement that includes the all-hadronic final state. The observed significance of the $\mathrm{t\bar{t}t\bar{t}}$ signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for $\mathrm{t\bar{t}t\bar{t}}$ production, with a measured cross section of 36 $^{+12}_{-11}$ fb. Combined with earlier CMS results in other final states, the signal significance is 4.0 standard deviations (3.2 expected). The combination returns an observed cross section of 17 $\pm$ 4 (stat) $\pm$ 3 (syst) fb, which is consistent with the standard model prediction.

A measurement is presented for the electroweak production of a W boson, a photon (γ), and two jets (j) in proton-proton collisions. The leptonic decay of the W boson is selected by requiring one identified electron or muon and large missing transverse momentum. The two jets are required to have large invariant dijet mass and large separation in pseudorapidity. The measurement is performed with the data collected by the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb−1. The cross section for the electroweak Wγjj production is 23.5+4.9−4.7 fb, whereas the total cross section for Wγjj production is 113±13 fb. Differential cross sections are also measured with the distributions unfolded to the particle level. All results are in agreement with the standard model expectations. Constraints are placed on anomalous quartic gauge couplings (aQGCs) in terms of dimension-8 effective field theory operators. These are the most stringent limits to date on the aQGCs parameters fM,2–5/Λ4 and fT,6–7/Λ4.Received 23 December 2022Accepted 1 March 2023DOI:https://doi.org/10.1103/PhysRevD.108.032017Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.© 2023 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Physical SystemsW & Z bosonsTechniquesHadron collidersParticles & Fields

A search for the lepton-flavor violating decay of the Higgs boson and potential additional Higgs bosons with a mass in the range 110-160 GeV to an e$^{\pm}μ^{\mp}$ pair is presented. The search is performed with a proton-proton collision dataset at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. No excess is observed for the Higgs boson. The observed (expected) upper limit on the e$^{\pm}μ^{\mp}$ branching fraction for it is determined to be 4.4 (4.7) $\times$ 10$^{-5}$ at 95% confidence level, the most stringent limit set thus far from direct searches. The largest excess of events over the expected background in the full mass range of the search is observed at an e$^{\pm}μ^{\mp}$ invariant mass of approximately 146 GeV with a local (global) significance of 3.8 (2.8) standard deviations.

We present an observation of photon-photon production of τ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404 μb^{-1} collected by the CMS experiment at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02 TeV. The γγ→τ^{+}τ^{-} process is observed for τ^{+}τ^{-} events with a muon and three charged hadrons in the final state. The measured fiducial cross section is σ(γγ→τ^{+}τ^{-})=4.8±0.6(stat)±0.5(syst) μb, where the second (third) term corresponds to the statistical (systematic) uncertainty in σ(γγ→τ^{+}τ^{-}) in agreement with leading-order QED predictions. Using σ(γγ→τ^{+}τ^{-}), we estimate a model-dependent value of the anomalous magnetic moment of the τ lepton of a_{τ}=0.001_{-0.089}^{+0.055}.

A simple and low-cost green synthesis method was optimized to prepare stable silver nanoparticles (AgNP) using aqueous Eucalyptus globulus leaves extract. This green method allows to obtain AgNP with spherical morphology and variable size around 25 nm, and it is dependent of the reaction temperature and concentration of the plant extract. AgNP stability was followed during 3 months by zeta potential measurements and a negative zeta range from −30.7 to −33.6 was determined. Biogenic-stabilized AgNP exhibited dual-functional properties as effective in environmental remediation with bacterial growth inhibition and dye photodegradation. Staphylococcus aureus and Escherichia coli were tested for antibacterial activity, and considerable inhibitory activity was found. High photocatalytic degradation of indigo carmine (IC) dye was performed in the presence of the AgNP as catalysts under sunlight irradiation. The degradation efficiency after 2 h of reaction was 37 %, 83 % and 98 % in the presence of UV light, visible light and sunlight irradiation, respectively. The germination of corn kernels test was used to determine the toxicity of the treated IC solutions and the results showed low toxicity after the photodegradation process.

A bstract The second-order ( v 2 ) and third-order ( v 3 ) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J / ψ, as well as prompt ψ(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of $$ \sqrt{s_{\textrm{NN}}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math> = 5 . 02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb − 1 recorded with the CMS detector. The J / ψ and ψ(2S) mesons are reconstructed using their dimuon decay channel. The v 2 and v 3 coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured v 2 values for prompt J / ψ mesons are found to be larger than those for nonprompt J / ψ mesons. The prompt J / ψ v 2 values at high p T are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J / ψ meson v 3 and prompt ψ(2S) v 2 and v 3 values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions.

The mass of the top quark is measured in 36.3fb-1 of LHC proton-proton collision data collected with the CMS detector at s=13TeV. The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables per event to extract the top quark mass. The top quark mass is measured to be 171.77±0.37GeV. This approach significantly improves the precision over previous measurements.

A bstract A measurement of the Higgs boson (H) production via vector boson fusion (VBF) and its decay into a bottom quark-antiquark pair ( $$ \textrm{b}\overline{\textrm{b}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ) is presented using proton-proton collision data recorded by the CMS experiment at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV and corresponding to an integrated luminosity of 90.8 fb − 1 . Treating the gluon-gluon fusion process as a background and constraining its rate to the value expected in the standard model (SM) within uncertainties, the signal strength of the VBF process, defined as the ratio of the observed signal rate to that predicted by the SM, is measured to be $$ {\mu}_{\textrm{Hb}\overline{\textrm{b}}}^{\textrm{qqh}}={1.01}_{-0.46}^{+0.55} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>μ</mml:mi> <mml:mrow> <mml:mi>Hb</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> <mml:mi>qqh</mml:mi> </mml:msubsup> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mn>1.01</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.46</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.55</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> . The VBF signal is observed with a significance of 2.4 standard deviations relative to the background prediction, while the expected significance is 2.7 standard deviations. Considering inclusive Higgs boson production and decay into bottom quarks, the signal strength is measured to be $$ {\mu}_{\textrm{Hb}\overline{\textrm{b}}}^{\textrm{incl}.}={0.99}_{-0.41}^{+0.48} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>μ</mml:mi> <mml:mrow> <mml:mi>Hb</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> <mml:mrow> <mml:mtext>incl</mml:mtext> <mml:mo>.</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mn>0.99</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.41</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.48</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , corresponding to an observed (expected) significance of 2.6 (2.9) standard deviations.

Abstract The identification of prompt and isolated muons, as well as muons from heavy-flavour hadron decays, is an important task. We developed two multivariate techniques to provide highly efficient identification for muons with transverse momentum greater than 10 GeV. One provides a continuous variable as an alternative to a cut-based identification selection and offers a better discrimination power against misidentified muons. The other one selects prompt and isolated muons by using isolation requirements to reduce the contamination from nonprompt muons arising in heavy-flavour hadron decays. Both algorithms are developed using 59.7 fb -1 of proton-proton collisions data at a centre-of-mass energy of √(s)=13 TeV collected in 2018 with the CMS experiment at the CERN LHC.

A bstract A search for dark matter particles is performed using events with a pair of W bosons and large missing transverse momentum. Candidate events are selected by requiring one or two leptons ( ℓ = electrons or muons). The analysis is based on proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC and corresponding to an integrated luminosity of 138 fb − 1 . No significant excess over the expected standard model background is observed in the ℓν qq and 2 ℓ 2 ν final states of the W + W − boson pair. Limits are set on dark matter production in the context of a simplified dark Higgs model, with a dark Higgs boson mass above the W + W − mass threshold. The dark matter phase space is probed in the mass range 100–300 GeV, extending the scope of previous searches. Current exclusion limits are improved in the range of dark Higgs masses from 160 to 250 GeV, for a dark matter mass of 200 GeV.

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton-proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13TeV. Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 20pb-1 of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z bosons for the integrated luminosity measurement is performed. The uncertainty in the extrapolation between two data sets, recorded in 2017 at low and high instantaneous luminosity, is less than 0.5%. We show that the Z boson rate measurement constitutes a precise method, complementary to traditional methods, with the potential to improve the measurement of the integrated luminosity.

The strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton-proton collisions at a center-of-mass energy of 13TeV. The analysis uses a data sample corresponding to a total integrated luminosity of 138fb-1 collected with the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm jets are tagged using the presence of a muon or a secondary vertex inside the jet. The W+c production cross section and the cross section ratio Rc±=σ(W++c¯)/σ(W-+c) are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in Rc±=0.950±0.005(stat)±0.010(syst). The measurements are compared with theoretical predictions up to next-to-next-to-leading order in perturbative quantum chromodynamics.

A test of lepton flavor universality in B$^{\pm}$ $\to$ K$^{\pm}\mu^+\mu^-$ and B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$ decays, as well as a measurement of differential and integrated branching fractions of a nonresonant B$^{\pm}$ $\to$ K$^{\pm}\mu^+\mu^-$ decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractions $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}\mu^+\mu^-$) to $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}$e$^+$e$^-$) is determined from the measured double ratio $R$(K) of these decays to the respective branching fractions of the B$^\pm$ $\to$ J/$\psi$K$^\pm$ with J/$\psi$ $\to$ $\mu^+\mu^-$ and e$^+$e$^-$ decays, which allow for significant cancellation of systematic uncertainties. The ratio $R$(K) is measured in the range 1.1 $\lt q^2 \lt$ 6.0 GeV$^2$, where $q$ is the invariant mass of the lepton pair, and is found to be $R$(K) = 0.78$^{+0.47}_{-0.23}$, in agreement with the standard model expectation $R$(K) $\approx$ 1. This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the same $q^2$ range, $\mathcal{B}$(B$^{\pm}$ $\to$ K$^{\pm}\mu^+\mu^-$) = (12.42 $\pm$ 0.68) $\times$ 10$^{-8}$, is consistent with the present world-average value and has a comparable precision.

Ultrarelativistic nuclear collisions create a strongly interacting state of hot and dense quark-gluon matter that exhibits a remarkable collective flow behavior with minimal viscous dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we extracted the speed of sound in this medium created using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb$^{-1}$. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of 0.241 $\pm$ 0.002 (stat) $\pm$ 0.016 (syst) in natural units. The effective medium temperature, estimated using the mean transverse momentum, is 219 $\pm$ 8 (syst) MeV. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions.

A search for dark matter in events with a displaced nonresonant muon pair and missing transverse momentum is presented. The analysis is performed using an integrated luminosity of 138 fb−1 of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV produced by the LHC in 2016–2018. No significant excess over the predicted backgrounds is observed. Upper limits are set on the product of the inelastic dark matter production cross section σ(pp→A′→χ1χ2) and the decay branching fraction B(χ2→χ1μ+μ−), where A′ is a dark photon and χ1 and χ2 are states in the dark sector with near mass degeneracy. This is the first dedicated collider search for inelastic dark matter.Received 19 May 2023Revised 24 September 2023Accepted 29 November 2023DOI:https://doi.org/10.1103/PhysRevLett.132.041802Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.© 2024 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Research AreasDark matterPhysical SystemsHypothetical particlesTechniquesHadron collidersParticles & Fields

Using proton-proton collision data corresponding to an integrated luminosity of 140 fb$^{-1}$ collected by the CMS experiment at $\sqrt{s}$ = 13 TeV, the $\Lambda_\text{b}^0$ $\to$ J/$\psi\Xi^-$K$^+$ decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the $\Lambda_\text{b}^0$ $\to$ $\psi$(2S)$\Lambda$ decay, is measured to be $\mathcal{B}$($\Lambda_\text{b}^0$ $\to$ J/$\psi\Xi^-$K$^+$)/$\mathcal{B}$( $\Lambda_\text{b}^0$ $\to$ $\psi$(2S)$\Lambda$) = [3.38 $\pm$ 1.02 $\pm$ 0.61 $\pm$ 0.03]%, where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in $\mathcal{B}$($\psi$(2S) $\to$ J/$\psi\pi^+\pi^-$) and $\mathcal{B}$($\Xi^-$ $\to$ $\Lambda\pi^-$).

A search is presented for new Higgs bosons in proton-proton (pp) collision events in which a same-sign top quark pair is produced in association with a jet, via the pp→tH/A→ttc‾ and pp→tH/A→ttu‾ processes. Here, H and A represent the extra scalar and pseudoscalar boson, respectively, of the second Higgs doublet in the generalized two-Higgs-doublet model (g2HDM). The search is based on pp collision data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb−1. Final states with a same-sign lepton pair in association with jets and missing transverse momentum are considered. New Higgs bosons in the 200–1000 GeV mass range and new Yukawa couplings between 0.1 and 1.0 are targeted in the search, for scenarios in which either H or A appear alone, or in which they coexist and interfere. No significant excess above the standard model prediction is observed. Exclusion limits are derived in the context of the g2HDM.

A search for long-lived particles (LLPs) decaying in the CMS muon detectors is presented. A data sample of proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 138 fb$^{-1}$ recorded at the LHC in 2016-2018, is used. The decays of LLPs are reconstructed as high multiplicity clusters of hits in the muon detectors. In the context of twin Higgs models, the search is sensitive to LLP masses from 0.4 to 55 GeV and a broad range of LLP decay modes, including decays to hadrons, $\tau$ leptons, electrons, or photons. No excess of events above the standard model background is observed. The most stringent limits to date from LHC data are set on the branching fraction of the Higgs boson decay to a pair of LLPs with masses below 10 GeV. This search also provides the best limits for various intervals of LLP proper decay length and mass. Finally, this search sets the first limits at the LHC on a dark quantum chromodynamic sector whose particles couple to the Higgs boson through gluon, Higgs boson, photon, vector, and dark-photon portals, and is sensitive to branching fractions of the Higgs boson to dark quarks as low as 2$\times$10$^{-3}$.

A combination of the results of several searches for the electroweak production of the supersymmetric partners of standard model bosons, and of charged leptons, is presented. All searches use proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC in 2016-2018. The analyzed data correspond to an integrated luminosity of up to 137 fb$^{-1}$. The results are interpreted in terms of simplified models of supersymmetry. Two new interpretations are added with this combination: a model spectrum with the bino as the lightest supersymmetric particle together with mass-degenerate higgsinos decaying to the bino and a standard model boson, and the compressed-spectrum region of a previously studied model of slepton pair production. Improved analysis techniques are employed to optimize sensitivity for the compressed spectra in the wino and slepton pair production models. The results are consistent with expectations from the standard model. The combination provides a more comprehensive coverage of the model parameter space than the individual searches, extending the exclusion by up to 125 GeV, and also targets some of the intermediate gaps in the mass coverage.

The azimuthal anisotropy of mesons in high-multiplicity proton-lead collisions is studied using data collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 8.16 TeV. The mesons are reconstructed using their dimuon decay channel. The anisotropy is characterized by the second Fourier harmonic coefficients, found using a two-particle correlation technique, in which the mesons are correlated with charged hadrons. A large pseudorapidity gap is used to suppress short-range correlations. Nonflow contamination from the dijet background is removed using a low-multiplicity subtraction method, and the results are presented as a function of transverse momentum. The azimuthal anisotropies are smaller than those found for charmonia in proton-lead collisions at the same collision energy, but are consistent with values found for mesons in lead-lead interactions at a nucleon-nucleon center-of-mass energy of 5.02 TeV.

Measurements of the elliptic (v2) and triangular (v3) azimuthal anisotropy coefficients are presented for mesons produced in hadron decays (nonprompt mesons) in lead-lead collisions at sNN=5.02TeV. The results are compared with previously published charm meson anisotropies measured using prompt mesons. The data were collected with the CMS detector in 2018 with an integrated luminosity of 0.58nb−1. Azimuthal anisotropy is sensitive to the interactions of quarks with the hot and dense medium created in heavy ion collisions. Comparing results for prompt and nonprompt mesons can assist in understanding the mass dependence of these interactions. The nonprompt results show lower magnitudes of v2 and v3 and weaker dependences on the meson transverse momentum and collision centrality than those found for prompt mesons. The results are in agreement with theoretical predictions that include a mass dependence in the interactions of quarks with the medium.

A search for pair production of scalar and vector leptoquarks (LQs) each decaying to a muon and a bottom quark is performed using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. No excess above standard model expectation is observed. Scalar (vector) LQs with masses less than 1810 (2120) GeV are excluded at 95% confidence level, assuming a 100% branching fraction of the LQ decaying to a muon and a bottom quark. These limits represent the most stringent to date.

The hydrodynamic flow-like behavior of charged hadrons in high-energy lead-lead collisions is studied through multiparticle correlations. The elliptic anisotropy values based on different orders of multiparticle cumulants, $v_{2}\{2k\}$, are measured up to the tenth order ($k$ = 5) as functions of the collision centrality at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 0.607 nb$^{-1}$. A hierarchy is observed between the coefficients, with $v_{2}\{2\} &gt; v_{2}\{4\} \gtrsim v_{2}\{6\} \gtrsim v_{2}\{8\} \gtrsim v_{2}\{10\}$. Based on these results, centrality-dependent moments for the fluctuation-driven event-by-event $v_{2}$ distribution are determined, including the skewness, kurtosis and, for the first time, superskewness. Assuming a hydrodynamic expansion of the produced medium, these moments directly probe the initial-state geometry in high-energy nucleus-nucleus collisions.

Two-particle Bose--Einstein momentum correlation functions are studied for charged-hadron pairs in lead-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{{s}_{\mathrm{NN}}}=5.02\phantom{\rule{4pt}{0ex}}\mathrm{TeV}$. The data sample, containing $4.27\ifmmode\times\else\texttimes\fi{}{10}^{9}$ minimum bias events corresponding to an integrated luminosity of 0.607 ${\text{nb}}^{\ensuremath{-}1}$, was collected by the CMS experiment in 2018. The experimental results are discussed in terms of a L\'evy-type source distribution. The parameters of this distribution are extracted as functions of particle pair average transverse mass and collision centrality. These parameters include the L\'evy index or shape parameter $\ensuremath{\alpha}$, the L\'evy scale parameter $R$, and the correlation strength parameter $\ensuremath{\lambda}$. The source shape, characterized by $\ensuremath{\alpha}$, is found to be neither Cauchy nor Gaussian, implying the need for a full L\'evy analysis. Similarly to what was previously found for systems characterized by Gaussian source radii, a hydrodynamical scaling is observed for the L\'evy $R$ parameter. The $\ensuremath{\lambda}$ parameter is studied in terms of the core-halo model.

A search for the production of long-lived particles in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC is presented. The search is based on data collected by the CMS experiment in 2016-2018, corresponding to a total integrated luminosity of 137 fb$^{-1}$. This search is designed to be sensitive to long-lived particles with mean proper decay lengths between 0.1 and 1000 $\mu$m, whose decay products produce a final state with at least one displaced vertex and missing transverse momentum. A machine learning algorithm, which improves the background rejection power by more than an order of magnitude, is applied to improve the sensitivity. The observation is consistent with the standard model background prediction, and the results are used to constrain split supersymmetry (SUSY) and gauge-mediated SUSY breaking models with different gluino mean proper decay lengths and masses. This search is the first CMS search that shows sensitivity to hadronically decaying long-lived particles from signals with mass differences between the gluino and neutralino below 100 GeV. It sets the most stringent limits to date for split-SUSY models and gauge-mediated SUSY breaking models with gluino proper decay length less than 6 $\mu$m.

The first observation of the decay $\Xi^-_\mathrm{b}$ $\to$ $\psi$(2S)$\Xi^-$ and measurement of the branching ratio of $\Xi^-_\mathrm{b}$ $\to$ $\psi$(2S)$\Xi^-$ to $\Xi^-_\mathrm{b}$ $\to$ J/$\psi$$\Xi^-$ are presented. The J/$\psi$ and $\psi$(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at $\sqrt{s}$ = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb$^{-1}$. The branching fraction ratio is measured to be $\mathcal{B}$($\Xi^-_\mathrm{b}$ $\to$ $\psi$(2S)$\Xi^-$)/$\mathcal{B}$($\Xi^-_\mathrm{b}$ $\to$ J/$\psi$$\Xi^-$) = 0.84$^{+0.21}_{-0.19}$ (stat) $\pm$ 0.10 (syst) $\pm$ 0.02 ($\mathcal{B}$), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the $\Xi_\mathrm{b}^{\ast{}0}$ baryon mass and natural width are also presented, using the $\Xi_\mathrm{b}^-\pi^+$ final state, where the $\Xi^-_\mathrm{b}$ baryon is reconstructed through the decays J/$\psi \Xi^-$, $\psi$(2S)$\Xi^-$, J/$\psi \Lambda$K$^-$, and J/$\psi \Sigma^0$K$^-$. Finally, the fraction of the $\Xi^-_\mathrm{b}$ baryons produced from $\Xi_\mathrm{b}^{\ast{}0}$ decays is determined.

A search is presented for baryon number violating interactions in top quark production and decay. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC with an integrated luminosity of 138 fb$^{-1}$. Candidate events are selected by requiring two oppositely-charged leptons (electrons or muons) and exactly one jet identified as originating from a bottom quark. Multivariate discriminants are used to separate the signal from the background. No significant deviation from the standard model prediction is observed. Upper limits are placed on the strength of baryon number violating couplings. For the first time the production of single top quarks via baryon number violating interactions is studied. This allows the search to set the most stringent constraints to date on the branching fraction of the top quark decay to a lepton, an up-type quark (u or c), and a down-type quark (d, s, or b). The results improve the previous bounds by three to six orders of magnitude based on the fermion flavor combination of the baryon number violating interactions.

A search for the production of a top quark in association with a photon and additional jets via flavor changing neutral current interactions is presented. The analysis uses proton-proton collision data recorded by the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb−1. The search is performed by looking for processes where a single top quark is produced in association with a photon, or a pair of top quarks where one of the top quarks decays into a photon and an up or charm quark. Events with an electron or a muon, a photon, one or more jets, and missing transverse momentum are selected. Multivariate analysis techniques are used to discriminate signal and standard model background processes. No significant deviation is observed over the predicted background. Observed (expected) upper limits are set on the branching fractions of top quark decays: B(t→uγ)<0.95×10−5 (1.20×10−5) and B(t→cγ)<1.51×10−5 (1.54×10−5) at 95% confidence level, assuming a single nonzero coupling at a time. The obtained limit for B(t→uγ) is similar to the current best limit, while the limit for B(t→cγ) is significantly tighter than previous results.Received 11 December 2023Accepted 29 January 2024DOI:https://doi.org/10.1103/PhysRevD.109.072004Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.© 2024 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Research AreasFlavor changing neutral currentsPhysical SystemsTop quarkTechniquesHadron collidersParticles & Fields

A search for the lepton flavor violating τ→3μ decay is performed using proton-proton collision events at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2017–2018, corresponding to an integrated luminosity of 97.7 fb−1. Tau leptons produced in both heavy-flavor hadron and W boson decays are exploited in the analysis. No evidence for the decay is observed. The results of this search are combined with an earlier null result based on data collected in 2016 to obtain a total integrated luminosity of 131 fb−1. The observed (expected) upper limits on the branching fraction B(τ→3μ) at confidence levels of 90 and 95% are 2.9×10−8 (2.4×10−8) and 3.6×10−8 (3.0×10−8), respectively.

A search is presented for charged, long-lived supersymmetric particles in final states with one or more disappearing tracks. The search is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the CERN LHC between 2016 and 2018, corresponding to an integrated luminosity of 137 fb−1. The search is performed over final states characterized by varying numbers of jets, b-tagged jets, electrons, and muons. The length of signal-candidate tracks in the plane perpendicular to the beam axis is used to characterize the lifetimes of wino- and Higgsino-like charginos produced in the context of the minimal supersymmetric standard model. The dE/dx energy loss of signal-candidate tracks is used to increase the sensitivity to charginos with a large mass and thus a small Lorentz boost. The observed results are found to be statistically consistent with the background-only hypothesis. Limits on the pair-production cross section of gluinos and squarks are presented in the framework of simplified models of supersymmetric particle production and decay, and for electroweakino production based on models of wino and Higgsino dark matter. The limits presented are the most stringent to date for scenarios with light third-generation squarks and a wino- or Higgsino-like dark matter candidate capable of explaining the observed dark matter relic density.5 MoreReceived 28 September 2023Accepted 14 February 2024DOI:https://doi.org/10.1103/PhysRevD.109.072007Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.© 2024 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Research AreasSupersymmetric modelsTechniquesHadron collidersParticles & Fields

A measurement is presented of a ratio observable that provides a measure of the azimuthal correlations among jets with large transverse momentum $p_\mathrm{T}$. This observable is measured in multijet events over the range of $p_\mathrm{T}$ = 360-3170 GeV based on data collected by the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 134 fb$^{-1}$. The results are compared with predictions from Monte Carlo parton-shower event generator simulations, as well as with fixed-order perturbative quantum chromodynamics (pQCD) predictions at next-to-leading-order (NLO) accuracy obtained with different parton distribution functions (PDFs) and corrected for nonperturbative and electroweak effects. Data and theory agree within uncertainties. From the comparison of the measured observable with the pQCD prediction obtained with the NNPDF3.1 NLO PDFs, the strong coupling at the Z boson mass scale is $\alpha_\mathrm{S}(m_\mathrm{Z})$ = 0.1177 $\pm$ 0.0013 (exp) $_{-0.0073}^{+0.0116}$ (theo) = 0.1177$_{-0.0074}^{+0.0117}$, where the total uncertainty is dominated by the scale dependence of the fixed-order predictions. A test of the running of $\alpha_\mathrm{S}(m_\mathrm{Z})$ in the TeV region shows no deviation from the expected NLO pQCD behaviour.

The performance of muon tracking, identification, triggering, momentum resolution, and momentum scale has been studied with the CMS detector at the LHC using data collected at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV in proton-proton (pp) and lead-lead (PbPb) collisions in 2017 and 2018, respectively, and at $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV in proton-lead (pPb) collisions in 2016. Muon efficiencies, momentum resolutions, and momentum scales are compared by focusing on how the muon reconstruction performance varies from relatively small occupancy pp collisions to the larger occupancies of pPb collisions and, finally, to the highest track multiplicity PbPb collisions. We find the efficiencies of muon tracking, identification, and triggering to be above 90% throughout most of the track multiplicity range. The momentum resolution and scale are unaffected by the detector occupancy. The excellent muon reconstruction of the CMS detector enables precision studies across all available collision systems.

The first search for the Z boson decay to $\tau\tau\mu\mu$ at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb$^{-1}$. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the Z $\to$ $\tau\tau\mu\mu$ to Z $\to$ 4$\mu$ branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two muons and two tau leptons, for the first time testing all such operators.

A search is presented for an extended Higgs sector with two new particles, X and $\phi$, in the process X $\to$ $\phi\phi$ $\to$ $(\gamma\gamma)(\gamma\gamma)$. Novel neural networks classify events with diphotons that are merged and determine the diphoton masses. The search uses LHC proton-proton collision data at $\sqrt{s}$ = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 138 fb$^{-1}$. No evidence of such resonances is seen. Upper limits are set on the production cross section versus the resonance masses, representing the most sensitive search in this channel.

The polarizations of promptly produced χc1 and χc2 mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8 TeV. The χc states are reconstructed via their radiative decays χc→J/ψγ, with the photons being measured through conversions to e+e−, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χc2 to χc1 yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ→μ+μ− decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum.Received 16 December 2019Revised 25 January 2020Accepted 26 March 2020DOI:https://doi.org/10.1103/PhysRevLett.124.162002Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.© 2020 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Hadron collidersTechniquesExperimental TechniquesParticle acceleratorsHadron collidersPhysical SystemsCharm quarkPropertiesPolarizationTechniquesHadron collidersParticles & Fields

The performance of a new point-of-care CE-IVD-marked isothermal lab-on-phone COVID-19 assay was assessed in comparison to a gold standard real-time reverse transcriptase-PCR method.The study was conducted following a nonprobability sampling of ≥16-year-old volunteers from three different laboratories, using direct mouthwash (N = 24) or nasopharyngeal (N = 191) clinical samples.The assay demonstrated 95.19% sensitivity and 100% specificity for detection of SARS-CoV-2 in direct nasopharyngeal crude samples and 78.95% sensitivity and 100% specificity in direct mouthwash crude samples. It also successfully detected currently predominant SARS-CoV-2 variants of concern (Beta B.1.351, Delta B.1.617.2, and Omicron B.1.1.529) and demonstrated to be inert against potential cross-reactions of other common respiratory pathogens that cause infections that present similar symptoms to COVID-19.This lab-on-phone pocket-sized assay relies on an isothermal amplification of SARS-CoV-2's N and E genes, taking just 50 minutes from sample to result, with only 2 minutes of hands-on time. It presents good performance when using direct nasopharyngeal crude samples, enabling a low-cost, real-time, rapid, and accurate identification of SARS-CoV-2 infections at the point of care, which is important for both clinical management and population screening, as a tool to break the chain of transmission of COVID-19 pandemic, especially in low-resources environments.

Twelve measurements of inclusive cross sections of W$^\pm$ and Z boson production, performed in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, are compared with perturbative quantum chromodynamics calculations at next-to-next-to-leading order (NNLO) accuracy obtained with the CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 parton distribution functions (PDFs). Data and theory agree well for all PDF sets, taking into account the experimental and theoretical uncertainties. A novel procedure is employed to extract the strong coupling constant at the Z pole mass from a detailed comparison of all the experimental fiducial cross sections to the corresponding NNLO theoretical predictions, yielding $\alpha_{S}(m_\mathrm{Z}) =$ 0.1163 $^{+0.0024}_{-0.0031}$ (CT14), 0.1072 $^{+0.0043}_{-0.0040}$ (HERAPDF2.0), 0.1186 $\pm$ 0.0025 (MMHT14), and 0.1147 $\pm$ 0.0023 (NNPDF3.0). Using the results obtained with the CT14 and MMHT14 PDFs, which yield the most robust and stable $\alpha_{S}(m_\mathrm{Z})$ extractions, a value $\alpha_{S}(m_\mathrm{Z}) =$ 0.1175 $^{+0.0025}_{-0.0028}$ is determined.

This work describes a green synthesis, the characterization, and biological evaluation of silver nanoparticles (AgNPs). The AgNPs suspension was synthesized using aqueous leaf extract of Eucalyptus grandis, which presented a characteristic band at 407 nm in the UV-Vis spectrum. The AgNPs presented a spherical shape and size of 9.7 ± 0.3 nm. The nanoparticles were stable over a month, indicating that E. grandis’ extract is suitable for their preparation and stabilization. The X-ray analysis showed that the crystallinity of AgNPs corresponded to the centered face phase of silver. The antibacterial and leishmanicidal activities of AgNPs were evaluated. The AgNPs presented antibacterial activity on the Gram-negative bacteria Escherichia coli at 53.9 µg mL–1. The leishmanicidal activity evaluation against promastigote forms of Leishmania infantum, Leishmania amazonensis, and Leishmania braziliensis showed that the biological response is dependent on the volume of AgNP suspension. It was demonstrated that L. infantum was more sensitive to the nanoparticle’s treatment than L. amazonensis and L. braziliensis. The treatment of L. infantum promastigotes with 150 µL of AgNP suspension reduced parasite growth by 67.9%, a result which was similar to the treatment with 1 (66.7%) or 2 µL (70.6%) of amphotericin B used as a positive control.

A search for pair production of the supersymmetric partner of the top quark, the top squark, in proton-proton collisions at $\sqrt{s}$ = 13 TeV is presented in final states containing at least one hadronically decaying tau lepton and large missing transverse momentum. This final state is highly sensitive to scenarios of supersymmetry in which the decay of the top squark to tau leptons is enhanced. The search uses a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$, which was recorded with the CMS detector during 2016-2018. No significant excess is observed with respect to the standard model predictions. Exclusion limits at 95% confidence level on the masses of the top squark and the lightest neutralino are presented under the assumptions of simplified models. The results probe top squark masses up to 1150 GeV for a nearly massless neutralino. This search covers a relatively less explored parameter space in the context of supersymmetry, and the exclusion limit is the most stringent to date for the model considered here.

A bstract The first search for nonresonant production of Higgs boson pairs (HH) with one H decaying into four leptons and the other into a pair of b quarks is presented, using proton-proton collisions recorded at a center-of-mass energy of $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 138 fb − 1 . A 95% confidence level upper limit of 32.4 is set on the signal strength modifier μ , defined as the ratio of the observed HH production rate in the $$ \textrm{HH}\to {\textrm{ZZ}}^{\ast}\textrm{b}\overline{\textrm{b}}\to 4\ell \textrm{b}\overline{\textrm{b}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>HH</mml:mi> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>ZZ</mml:mi> <mml:mo>∗</mml:mo> </mml:msup> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>→</mml:mo> <mml:mn>4</mml:mn> <mml:mi>ℓ</mml:mi> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> decay channel to the standard model (SM) expectation. Possible modifications of the H trilinear coupling λ HHH with respect to the SM value are investigated. The coupling modifier κ λ , defined as λ HHH divided by its SM prediction, is constrained to be within the observed (expected) range − 8 . 8 ( − 9 . 8) &lt; κ λ &lt; 13 . 4 (15 . 0) at 95% confidence level.

A bstract A measurement of the top quark pole mass $$ {m}_{\textrm{t}}^{\textrm{pole}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>m</mml:mi> <mml:mi>t</mml:mi> <mml:mtext>pole</mml:mtext> </mml:msubsup> </mml:math> in events where a top quark-antiquark pair ( $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ) is produced in association with at least one additional jet ( $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> +jet) is presented. This analysis is performed using proton-proton collision data at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV collected by the CMS experiment at the CERN LHC, corresponding to a total integrated luminosity of 36.3 fb − 1 . Events with two opposite-sign leptons in the final state (e + e − , μ + μ − , e ± μ ∓ ) are analyzed. The reconstruction of the main observable and the event classification are optimized using multivariate analysis techniques based on machine learning. The production cross section is measured as a function of the inverse of the invariant mass of the $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> +jet system at the parton level using a maximum likelihood unfolding. Given a reference parton distribution function (PDF), the top quark pole mass is extracted using the theoretical predictions at next-to-leading order. For the ABMP16NLO PDF, this results in $$ {m}_{\textrm{t}}^{\textrm{pole}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>m</mml:mi> <mml:mi>t</mml:mi> <mml:mtext>pole</mml:mtext> </mml:msubsup> </mml:math> = 172 . 93 ± 1 . 36 GeV.

The charge-parity ($CP$) structure of the Yukawa interaction between the Higgs (H) boson and the top quark is measured in a data sample enriched in the $\mathrm{t\bar{t}}$ and tH associated production, using 138 fb$^{-1}$ of data collected in proton-proton collisions at $\sqrt{s}$ = 13 TeV by the CMS experiment at the CERN LHC. The study targets events where the H boson decays via H $\to$ WW or H $\to$ $\tau\tau$ and the top quarks decay via t $\to$ Wb: the W bosons decay either leptonically or hadronically, and final states characterized by the presence of at least two leptons are studied. Machine learning techniques are applied to these final states to enhance the separation of $CP$-even from $CP$-odd scenarios. Two-dimensional confidence regions are set on $\kappa_\mathrm{t}$ and $\tilde{\kappa}_\mathrm{t}$, which are respectively defined as the $CP$-even and $CP$-odd top-Higgs Yukawa coupling modifiers. No significant fractional $CP$-odd contributions, parameterized by the quantity $\lvert{f_{CP}^{\mathrm{Htt}}}\rvert$ are observed; the parameter is determined to be $\lvert{f_{CP}^{\mathrm{Htt}}}\rvert$ = 0.59 with an interval of (0.24, 0.81) at 68% confidence level. The results are combined with previous results covering the H $\to$ ZZ and H $\to$ $\gamma\gamma$ decay modes, yielding two- and one-dimensional confidence regions on $\kappa_\mathrm{t}$ and $\tilde{\kappa}_\mathrm{t}$, while $\lvert{f_{CP}^{\mathrm{Htt}}}\rvert$ is determined to be $\lvert{f_{CP}^{\mathrm{Htt}}}\rvert$ = 0.28 with an interval of $\lvert{f_{CP}^{\mathrm{Htt}}}\rvert$ $\lt$ 0.55 at 68% confidence level, in agreement with the standard model $CP$-even prediction of $\lvert{f_{CP}^{\mathrm{Htt}}}\rvert$ = 0.

A search for the standard model (SM) Higgs boson (H) produced with transverse momentum (p_{T}) greater than 450 GeV and decaying to a charm quark-antiquark (cc[over ¯]) pair is presented. The search is performed using proton-proton collision data collected at sqrt[s]=13 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb^{-1}. Boosted H→cc[over ¯] decay products are reconstructed as a single large-radius jet and identified using a deep neural network charm tagging technique. The method is validated by measuring the Z→cc[over ¯] decay process, which is observed in association with jets at high p_{T} for the first time with a signal strength of 1.00_{-0.14}^{+0.17}(syst)±0.08(theo)±0.06(stat), defined as the ratio of the observed process rate to the SM expectation. The observed (expected) upper limit on σ(H)B(H→cc[over ¯]) is set at 47 (39) times the SM prediction at 95% confidence level.

Measurements of the inclusive and differential fiducial cross sections for the Higgs boson production in the H $\to$ ZZ $\to$ 4$\ell$ ($\ell$ = e,$\mu$) decay channel are presented. The results are obtained from the analysis of proton-proton collision data recorded by the CMS experiment at the CERN LHC at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The measured inclusive fiducial cross section is 2.73 $\pm$ 0.26 fb, in agreement with the standard model expectation of 2.86 $\pm$ 0.1 fb. Differential cross sections are measured as a function of several kinematic observables sensitive to the Higgs boson production and decay to four leptons. A set of double-differential measurements is also performed, yielding a comprehensive characterization of the four leptons final state. Constraints on the Higgs boson trilinear coupling and on the bottom and charm quark coupling modifiers are derived from its transverse momentum distribution. All results are consistent with theoretical predictions from the standard model.

The first observation of the production of W ± W ± bosons from double parton scattering processes using same-sign electron-muon and dimuon events in proton-proton collisions is reported.The data sample corresponds to an integrated luminosity of 138 fb -1 recorded at a center-of-mass energy of 13 TeV using the CMS detector at the CERN LHC.Multivariate discriminants are used to distinguish the signal process from the main backgrounds.A binned maximum likelihood fit is performed to extract the signal cross section.The measured cross section for production of same-sign W bosons decaying leptonically is 80.7 ± 11.2 (stat) +9.5 -8.6 (syst) ± 12.1 (model) fb, whereas the measured fiducial cross section is 6.28 ± 0.81 (stat) ± 0.69 (syst) ± 0.37 (model) fb.The observed significance of the signal is 6.2 standard deviations above the background-only hypothesis.

We present the first direct search for exotic Higgs boson decays H→AA, A→γγ in events with two photonlike objects. The hypothetical particle A is a low-mass spin-0 particle decaying promptly to a merged diphoton reconstructed as a single photonlike object. We analyze the data collected by the CMS experiment at sqrt[s]=13 TeV corresponding to an integrated luminosity of 136 fb^{-1}. No excess above the estimated background is found. We set upper limits on the branching fraction B(H→AA→4γ) of (0.9-3.3)×10^{-3} at 95% confidence level for masses of A in the range 0.1-1.2 GeV.

A bstract The first measurement of the top quark pair ( $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ) production cross section in proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 . 6 TeV is presented. Data recorded with the CMS detector at the CERN LHC in Summer 2022, corresponding to an integrated luminosity of 1 . 21 fb − 1 , are analyzed. Events are selected with one or two charged leptons (electrons or muons) and additional jets. A maximum likelihood fit is performed in event categories defined by the number and flavors of the leptons, the number of jets, and the number of jets identified as originating from b quarks. An inclusive $$ \textrm{t}\overline{\textrm{t}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> production cross section of 881 ± 23 (stat + syst) ± 20 (lumi) pb is measured, in agreement with the standard model prediction of $$ {924}_{-40}^{+32} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mn>924</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>40</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>32</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> pb.

The first search is presented for vector-like leptons (VLLs) in the context of the "4321 model", an ultraviolet-complete model with the potential to explain existing B physics measurements that are in tension with standard model predictions. The analyzed data, corresponding to an integrated luminosity of 96.5fb−1, were recorded in 2017 and 2018 with the CMS detector at the LHC in proton-proton collisions at s=13TeV. Final states with ≥3 b -tagged jets and two third-generation leptons (ττ, τντ, or ντντ) are considered. Upper limits are derived on the VLL production cross section in the VLL mass range 500–1050 GeV. The maximum likelihood fit prefers the presence of signal at the level of 2.8 standard deviations, for a representative VLL mass point of 600 GeV. As a consequence, the observed upper limits are approximately double the expected limits.

Quasireal photons exchanged in relativistic heavy ion interactions are powerful probes of the gluonic structure of nuclei. The coherent J/ψ photoproduction cross section in ultraperipheral lead-lead collisions is measured as a function of photon-nucleus center-of-mass energies per nucleon (W_{γN}^{Pb}) over a wide range of 40<W_{γN}^{Pb}<400 GeV. Results are obtained using data at the nucleon-nucleon center-of-mass energy of 5.02 TeV collected by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 1.52 nb^{-1}. The cross section is observed to rise rapidly at low W_{γN}^{Pb}, and plateau above W_{γN}^{Pb}≈40 GeV, up to 400 GeV, entering a new regime of small Bjorken-x (≈6×10^{-5}) gluons being probed in a heavy nucleus. The observed energy dependence is not predicted by current quantum chromodynamic models.

A bstract A search for new physics in top quark production with additional final-state leptons is performed using data collected by the CMS experiment in proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV at the LHC during 2016–2018. The data set corresponds to an integrated luminosity of 138 fb − 1 . Using the framework of effective field theory (EFT), potential new physics effects are parametrized in terms of 26 dimension-six EFT operators. The impacts of EFT operators are incorporated through the event-level reweighting of Monte Carlo simulations, which allows for detector-level predictions. The events are divided into several categories based on lepton multiplicity, total lepton charge, jet multiplicity, and b-tagged jet multiplicity. Kinematic variables corresponding to the transverse momentum ( p T ) of the leading pair of leptons and/or jets as well as the p T of on-shell Z bosons are used to extract the 95% confidence intervals of the 26 Wilson coefficients corresponding to these EFT operators. No significant deviation with respect to the standard model prediction is found.

A bstract A search for direct production of low-mass dimuon resonances is performed using $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV proton-proton collision data collected by the CMS experiment during the 2017–2018 operation of the CERN LHC with an integrated luminosity of 96 . 6 fb − 1 . The search exploits a dedicated high-rate trigger stream that records events with two muons with transverse momenta as low as 3 GeV but does not include the full event information. The search is performed by looking for narrow peaks in the dimuon mass spectrum in the ranges of 1.1–2.6 GeV and 4.2–7.9 GeV. No significant excess of events above the expectation from the standard model background is observed. Model-independent limits on production rates of dimuon resonances within the experimental fiducial acceptance are set. Competitive or world’s best limits are set at 90% confidence level for a minimal dark photon model and for a scenario with two Higgs doublets and an extra complex scalar singlet (2HDM+S). Values of the squared kinetic mixing coefficient ε 2 in the dark photon model above 10 − 6 are excluded over most of the mass range of the search. In the 2HDM+S, values of the mixing angle sin( θ H ) above 0.08 are excluded over most of the mass range of the search with a fixed ratio of the Higgs doublets vacuum expectation tan β = 0 . 5.

Quasireal photons exchanged in relativistic heavy ion interactions are powerful probes of the gluonic structure of nuclei. The coherent J/ψ photoproduction cross section in ultraperipheral lead-lead collisions is measured as a function of photon-nucleus center-of-mass energies per nucleon (WγNPb) over a wide range of 40<WγNPb<400 GeV. Results are obtained using data at the nucleon-nucleon center-of-mass energy of 5.02 TeV collected by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 1.52 nb−1. The cross section is observed to rise rapidly at low WγNPb, and plateau above WγNPb≈40 GeV, up to 400 GeV, entering a new regime of small Bjorken-x (≈6×10−5) gluons being probed in a heavy nucleus. The observed energy dependence is not predicted by current quantum chromodynamic models.Received 29 March 2023Revised 17 August 2023Accepted 26 October 2023DOI:https://doi.org/10.1103/PhysRevLett.131.262301Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.© 2023 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Research AreasPhoton productionRelativistic heavy-ion collisionsPhysical SystemsGluonsTechniquesHadron collidersParticles & FieldsNuclear Physics