Georgios Krintiras

A search for invisible decays of a Higgs boson is performed using proton-proton collision data collected with the CMS detector at the LHC in 2016 at a center-of-mass energy , corresponding to an integrated luminosity of 35.9. The search targets the production of a Higgs boson via vector boson fusion. The data are found to be in agreement with the background contributions from standard model processes. An observed (expected) upper limit of 0.33 (0.25), at 95% confidence level, is placed on the branching fraction of the Higgs boson decay to invisible particles, assuming standard model production rates and a Higgs boson mass of 125.09 GeV. Results from a combination of this analysis and other direct searches for invisible decays of the Higgs boson, performed using data collected at , 8, and 13 TeV, are presented. An observed (expected) upper limit of 0.19 (0.15), at 95% confidence level, is set on the branching fraction of invisible decays of the Higgs boson. The combined limit represents the most stringent bound on the invisible branching fraction of the Higgs boson reported to date. This result is also interpreted in the context of Higgs-portal dark matter models, in which upper bounds are placed on the spin-independent dark-matter-nucleon scattering cross section.

Signals consistent with the B+c(2S) and B*+c(2S) states are observed in proton-proton collisions at √s=13 TeV, in an event sample corresponding to an integrated luminosity of 143 fb−1, collected by the CMS experiment during the 2015–2018 LHC running periods. These excited ¯bc states are observed in the B+cπ+π− invariant mass spectrum, with the ground state B+c reconstructed through its decay to J/ψπ+. The two states are reconstructed as two well-resolved peaks, separated in mass by 29.1±1.5(stat)±0.7(syst) MeV. The observation of two peaks, rather than one, is established with a significance exceeding five standard deviations. The mass of the B+c(2S) meson is measured to be 6871.0±1.2(stat)±0.8(syst)±0.8(B+c) MeV, where the last term corresponds to the uncertainty in the world-average B+c mass.Received 1 February 2019Revised 18 February 2019DOI:https://doi.org/10.1103/PhysRevLett.122.132001Published 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.© 2019 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Research AreasParticle productionPhysical SystemsBottom quarkMesonsTechniquesHadron collidersParticles & Fields

Based on the gauge transformation between the corresponding Lax pair, we derive a Darboux transformation of the coupled massive Thirring system.As an application, using the Darboux transformation and the reduction technique, various exact solutions for the coupled massive Thirring system and the classical massive Thirring model are obtained, including one-soliton solution, two-soliton solution, periodic solution, and others.

Normalised multi-differential cross sections for top quark pair ($\mathrm{t\overline{t}}$) production are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV using events containing two oppositely charged leptons. The analysed data were recorded with the CMS detector in 2016 and correspond to an integrated luminosity of 35.9 fb$^{-1}$. The double-differential $\mathrm{t\overline{t}}$ cross section is measured as a function of the kinematic properties of the top quark and of the $\mathrm{t\overline{t}}$ system at parton level in the full phase space. A triple-differential measurement is performed as a function of the invariant mass and rapidity of the $\mathrm{t\overline{t}}$ system and the multiplicity of additional jets at particle level. The data are compared to predictions of Monte Carlo event generators that complement next-to-leading-order (NLO) quantum chromodynamics (QCD) calculations with parton showers. Together with a fixed-order NLO QCD calculation, the triple-differential measurement is used to extract values of the strong coupling strength $\alpha_S$ and the top quark pole mass ($m_\mathrm{T}^\text{pole}$) using several sets of parton distribution functions (PDFs). Furthermore, a simultaneous fit of the PDFs, $\alpha_S$, and $m_\mathrm{T}^\text{pole}$ is performed at NLO, demonstrating that the new data have significant impact on the gluon PDF, and at the same time allow an accurate determination of $\alpha_S$ and $m_\mathrm{T}^\text{pole}$. The values $\alpha_S(m_\mathrm{Z})$ = 0.1135 $^{+0.0021}_{-0.0017}$ and $m_\mathrm{T}^\text{pole}$ = 170.5 $\pm$ 0.8 GeV are extracted, which account for experimental and theoretical uncertainties, the latter being estimated from NLO scale variations. Possible effects from Coulomb and soft-gluon resummation near the $\mathrm{t\overline{t}}$ production threshold are neglected in these parameter extractions.

Measurements of the top quark polarization and top quark pair (t¯t) spin correlations are presented using events containing two oppositely charged leptons (e+e−, e±μ∓, or μ+μ−) produced in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were recorded by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.9 fb−1. A set of parton-level normalized differential cross sections, sensitive to each of the independent coefficients of the spin-dependent parts of the t¯t production density matrix, is measured for the first time at 13 TeV. The measured distributions and extracted coefficients are compared with standard model predictions from simulations at next-to-leading-order (NLO) accuracy in quantum chromodynamics (QCD), and from NLO QCD calculations including electroweak corrections. All measurements are found to be consistent with the expectations of the standard model. The normalized differential cross sections are used in fits to constrain the anomalous chromomagnetic and chromoelectric dipole moments of the top quark to −0.24<CtG/Λ2<0.07 TeV−2 and −0.33<CItG/Λ2<0.20 TeV−2, respectively, at the 95% confidence level.9 MoreReceived 8 July 2019DOI:https://doi.org/10.1103/PhysRevD.100.072002Published 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.© 2019 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Hadron collidersTechniquesExperimental TechniquesParticle acceleratorsHadron collidersPhysical SystemsTop quarkTechniquesHadron collidersParticles & Fields

A search for anomalous electroweak production of WW, WZ, and ZZ boson pairs in association with two jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV at the LHC is reported. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$ collected with the CMS detector. Events are selected by requiring two jets with large rapidity separation and invariant mass, one or two leptons (electrons or muons), and a W or Z boson decaying hadronically. No excess of events with respect to the standard model background predictions is observed and constraints on the structure of quartic vector boson interactions in the framework of dimension-8 effective field theory operators are reported. Stringent limits on parameters of the effective field theory operators are obtained. The observed 95% confidence level limits for the S0, M0, and T0 operators are $-$2.7 $<$ f$_{\mathrm{S0}}/ \Lambda^{4}$ $<$ 2.7, $-$1.0 $<$ f$_{\mathrm{M0}}/ \Lambda^{4}$ $<$ 1.0, and $-$0.17 $<$ f$_{\mathrm{T0}}/ \Lambda^{4}$ $<$ 0.16, in units of TeV$^{-4}$. Constraints are also reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass from 600 to 2000 GeV. The results are interpreted in the context of the Georgi-Machacek model.

The transverse momentum (pT) spectra of inclusively produced Λc+ baryons are measured via the exclusive decay channel Λc+→pK−π+ using the CMS detector at the LHC. Spectra are measured as a function of transverse momentum in proton-proton (pp) and lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measurement is performed within the Λc+ rapidity interval |y|<1 in the pT range of 5–20GeV/c in pp and 10–20GeV/c in PbPb collisions. The observed yields of Λc+ for pT of 10–20GeV/c suggest a suppression in central PbPb collisions compared to pp collisions scaled by the number of nucleon-nucleon (NN) interactions. The Λc+/D0 production ratio in pp collisions is compared to theoretical models. In PbPb collisions, this ratio is consistent with the result from pp collisions in their common pT range.

A search is presented for pairs of light pseudoscalar bosons, in the mass range from 4 to 15 GeV, produced from decays of the 125 GeV Higgs boson. The decay modes considered are final states that arise when one of the pseudoscalars decays to a pair of tau leptons, and the other one either into a pair of tau leptons or muons. The search is based on proton-proton collisions collected by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV that correspond to an integrated luminosity of 35.9 fb−1. The 2μ2τ and 4τ channels are used in combination to constrain the product of the Higgs boson production cross section and the branching fraction into 4τ final state, σB, exploiting the linear dependence of the fermionic coupling strength of pseudoscalar bosons on the fermion mass. No significant excess is observed beyond the expectation from the standard model. The observed and expected upper limits at 95% confidence level on σB, relative to the standard model Higgs boson production cross section, are set respectively between 0.022 and 0.23 and between 0.027 and 0.19 in the mass range probed by the analysis.

This document summarises proposed searches for new physics accessible in the heavy-ion mode at the CERN Large Hadron Collider (LHC), both through hadronic and ultraperipheral $\gamma\gamma$ interactions, and that have a competitive or, even, unique discovery potential compared to standard proton-proton collision studies. Illustrative examples include searches for new particles -- such as axion-like pseudoscalars, radions, magnetic monopoles, new long-lived particles, dark photons, and sexaquarks as dark matter candidates -- as well as new interactions, such as non-linear or non-commutative QED extensions. We argue that such interesting possibilities constitute a well-justified scientific motivation, complementing standard quark-gluon-plasma physics studies, to continue running with ions at the LHC after the Run-4, i.e. beyond 2030, including light and intermediate-mass ion species, accumulating nucleon-nucleon integrated luminosities in the accessible fb$^{-1}$ range per month.

A bstract A search for supersymmetric particles produced in the vector boson fusion topology in proton-proton collisions is presented. The search targets final states with one or zero leptons, large missing transverse momentum, and two jets with a large separation in rapidity. The data sample corresponds to an integrated luminosity of 35.9 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 in 2016 with the CMS detector at the LHC. The observed dijet invariant mass and lepton-neutrino transverse mass spectra are found to be consistent with the standard model predictions. Upper limits are set on the cross sections for chargino $$ \left({\tilde{\upchi}}_1^{\pm}\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mfenced> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>1</mml:mn> <mml:mo>±</mml:mo> </mml:msubsup> </mml:mfenced> </mml:math> and neutralino $$ \left({\tilde{\upchi}}_2^0\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mfenced> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:mfenced> </mml:math> production with two associated jets. For a compressed mass spectrum scenario in which the $$ {\tilde{\upchi}}_1^{\pm } $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>1</mml:mn> <mml:mo>±</mml:mo> </mml:msubsup> </mml:math> and $$ {\tilde{\upchi}}_2^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> decays proceed via a light slepton and the mass difference between the lightest neutralino $$ {\tilde{\upchi}}_1^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>1</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> and the mass-degenerate particles $$ {\tilde{\upchi}}_1^{\pm } $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>1</mml:mn> <mml:mo>±</mml:mo> </mml:msubsup> </mml:math> and $$ {\tilde{\upchi}}_2^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mover> <mml:mi>χ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mn>2</mml:mn> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> is 1 (30) GeV, the most stringent lower limit to date of 112 (215) GeV is set on the mass of these latter two particles.

The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

A study is presented of anomalous HVV interactions of the Higgs boson, including its CP properties. The study uses Higgs boson candidates produced mainly in vector boson fusion and gluon fusion that subsequently decay to a pair of τ leptons. The data were recorded by the CMS experiment at the LHC in 2016 at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 35.9 fb−1. A matrix element technique is employed for the analysis of anomalous interactions. The results are combined with those from the H→4ℓ decay channel presented earlier, yielding the most stringent constraints on anomalous Higgs boson couplings to electroweak vector bosons expressed as effective cross section fractions and phases: the CP-violating parameter fa3cos(ϕa3)=(0.00±0.27)×10−3 and the CP-conserving parameters fa2cos(ϕa2)=(0.08+1.04−0.21)×10−3, fΛ1cos(ϕΛ1)=(0.00+0.53−0.09)×10−3, and fZγΛ1cos(ϕZγΛ1)=(0.0+1.1−1.3)×10−3. The current dataset does not allow for precise constraints on CP properties in the gluon fusion process. The results are consistent with standard model expectations.4 MoreReceived 16 March 2019DOI:https://doi.org/10.1103/PhysRevD.100.112002Published 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.© 2019 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Physical SystemsHiggs bosonsTechniquesHadron collidersParticles & Fields

A search for a light charged Higgs boson (H+) decaying to a W boson and a CP-odd Higgs boson (A) in final states with eμμ or μμμ is performed using data from pp collisions at √s=13 TeV, recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb−1. In this search, it is assumed that the H+ boson is produced in decays of top quarks, and the A boson decays to two oppositely charged muons. The presence of signals for H+ boson masses between 100 and 160 GeV and A boson masses between 15 and 75 GeV is investigated. No evidence for the production of the H+ boson is found. Upper limits at 95% confidence level are obtained on the combined branching fraction for the decay chain, t→bH+→bW+A→bW+μ+μ−, of 1.9×10−6 to 8.6×10−6, depending on the masses of the H+ and A bosons. These are the first limits for these decay modes of the H+ and A bosons.Received 18 May 2019Revised 19 July 2019DOI:https://doi.org/10.1103/PhysRevLett.123.131802Published 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.© 2019 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Physical SystemsHiggs bosonsHypothetical gauge bosonsTop quarkTechniquesHadron collidersParticles & Fields

A search is performed for neutral non-standard-model Higgs bosons decaying to two muons in the context of the minimal supersymmetric standard model (MSSM). Proton-proton collision data recorded by the CMS experiment at the CERN Large Hadron Collider at a center-of-mass energy of 13 TeV were used, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The search is sensitive to neutral Higgs bosons produced via the gluon fusion process or in association with a $\mathrm{b\overline{b}}$ quark pair. No significant deviations from the standard model expectation are observed. Upper limits at 95% confidence level are set in the context of the $m_\mathrm{h}^{\text{mod+}}$ and phenomenological MSSM scenarios on the parameter $\tan\beta$ as a function of the mass of the pseudoscalar A boson, in the range from 130 to 600 GeV. The results are also used to set a model-independent limit on the product of the branching fraction for the decay into a muon pair and the cross section for the production of a scalar neutral boson, either via gluon fusion, or in association with b quarks, in the mass range from 130 to 1000 GeV.

A statistical combination of searches for heavy resonances decaying to pairs of bosons or leptons is presented. The data correspond to an integrated luminosity of 35.9 fb−1 collected during 2016 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. The data are found to be consistent with expectations from the standard model background. Exclusion limits are set in the context of models of spin-1 heavy vector triplets and of spin-2 bulk gravitons. For mass-degenerate W′ and Z′ resonances that predominantly couple to the standard model gauge bosons, the mass exclusion at 95% confidence level of heavy vector bosons is extended to 4.5 TeV as compared to 3.8 TeV determined from the best individual channel. This excluded mass increases to 5.0 TeV if the resonances couple predominantly to fermions.

The observation of single top quark production in association with a Z boson and a quark (tZq) is reported. Events from proton-proton collisions at a center-of-mass energy of 13 TeV containing three charged leptons (either electrons or muons) and at least two jets are analyzed. The data were collected with the CMS detector in 2016 and 2017 and correspond to an integrated luminosity of 77.4fb−1. The increased integrated luminosity, a multivariate lepton identification, and a redesigned analysis strategy improve significantly the sensitivity of the analysis compared to previous searches for tZq production. The tZq signal is observed with a significance well over 5 standard deviations. The measured tZq production cross section is σ(pp→tZq→tℓ+ℓ−q)=111±13(stat)+11−9(syst) fb, for dilepton invariant masses above 30 GeV, in agreement with the standard model expectation.Received 14 December 2018Revised 27 February 2019DOI:https://doi.org/10.1103/PhysRevLett.122.132003Published 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.© 2019 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Physical SystemsTop quarkW & Z bosonsTechniquesHadron collidersParticles & Fields

An embedding technique is presented to estimate standard model ττ backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed μμ events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS . Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at √s=13 TeV corresponding to an integrated luminosity of 41.5 fb−1.

A search for narrow low-mass resonances decaying to quark-antiquark pairs is presented. The search is based on proton-proton collision events collected at 13 TeV by the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 35.9 fb^{-1}, recorded in 2016. The search considers the case where the resonance has high transverse momentum due to initial-state radiation of a hard photon. To study this process, the decay products of the resonance are reconstructed as a single large-radius jet with two-pronged substructure. The signal would be identified as a localized excess in the jet invariant mass spectrum. No evidence for such a resonance is observed in the mass range 10 to 125 GeV. Upper limits at the 95% confidence level are set on the coupling strength of resonances decaying to quark pairs. The results obtained with this photon trigger strategy provide the first direct constraints on quark-antiquark resonance masses below 50 GeV obtained at a hadron collider.

The average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities -6.6<η<-5.2 in proton-proton collisions at a centre-of-mass energy s=13TeV . The results are presented as a function of the charged particle multiplicity in the region |η|<2 . This measurement is sensitive to correlations induced by the underlying event structure over a very wide pseudorapidity region. The predictions of Monte Carlo event generators commonly used in collider experiments and ultra-high energy cosmic ray physics are compared to the data. All generators considered overestimate the fraction of energy going into hadrons.

A bstract A search for new massive particles decaying into a pair of Higgs bosons in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. Data were collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb − 1 . The search is performed for resonances with a mass between 0.8 and 3.5 TeV using events in which one Higgs boson decays into a bottom quark pair and the other decays into two W bosons that subsequently decay into a lepton, a neutrino, and a quark pair. The Higgs boson decays are reconstructed with techniques that identify final state quarks as substructure within boosted jets. The data are consistent with standard model expectations. Exclusion limits are placed on the product of the cross section and branching fraction for generic spin-0 and spin-2 massive resonances. The results are interpreted in the context of radion and bulk graviton production in models with a warped extra spatial dimension. These are the best results to date from searches for an HH resonance decaying to this final state, and they are comparable to the results from searches in other channels for resonances with masses below 1.5 TeV.

A bstract A general search is presented for a low-mass τ − τ + resonance produced in association with a bottom quark. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb −1 . The data are consistent with the standard model expectation. Upper limits at 95% confidence level on the cross section times branching fraction are determined for two signal models: a light pseudoscalar Higgs boson decaying to a pair of τ leptons produced in association with bottom quarks, and a low-mass boson X decaying to a τ -lepton pair that is produced in the decay of a bottom-like quark B such that B → bX. Masses between 25 and 70 GeV are probed for the light pseudoscalar boson with upper limits ranging from 250 to 44 pb. Upper limits from 20 to 0.3 pb are set on B masses between 170 and 450 GeV for X boson masses between 20 and 70 GeV.

A bstract Results are reported of a search for supersymmetry in final states with photons and missing transverse momentum in proton-proton collisions at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb −1 collected at a center-of-mass energy of 13 TeV using the CMS detector. The results are interpreted in the context of models of gauge-mediated supersymmetry breaking. Production cross section limits are set on gluino and squark pair production in this framework. Gluino masses below 1.86 TeV and squark masses below 1.59 TeV are excluded at 95% confidence level.

A measurement is presented of electroweak (EW) production of a W boson in association with two jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The data sample was recorded by the CMS Collaboration at the LHC and corresponds to an integrated luminosity of 35.9 fb$^{-1}$. The measurement is performed for the $\ell\nu$jj final state (with $\ell\nu$ indicating a lepton-neutrino pair, and j representing the quarks produced in the hard interaction) in a kinematic region defined by invariant mass $m_\mathrm{jj}$ $>$ 120 GeV and transverse momenta $p_\mathrm{T j}$ $>$ 25 GeV. The cross section of the process is measured in the electron and muon channels yielding $\sigma_\mathrm{EW}$(Wjj) = 6.23 $\pm$ 0.12 (stat) $\pm$ 0.61 (syst) pb per channel, in agreement with leading-order standard model predictions. The additional hadronic activity of events in a signal-enriched region is studied, and the measurements are compared with predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. Limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are $-$2.3 $<$ $c_{\mathrm{WWW}}/\Lambda^2$ $<$ 2.5 TeV$^{-2}$, $-$8.8 $<$ $c_{\mathrm{W}}/\Lambda^2$ $<$ 16 TeV$^{-2}$, and $-$45 $<$ $c_{\mathrm{B}}/\Lambda^2$ $<$ 46 TeV$^{-2}$. These results are combined with the CMS EW Zjj analysis, yielding the constraint on the $c_{\mathrm{WWW}}$ coupling: $-$1.8 $<$ $c_{\mathrm{WWW}}/\Lambda^2$ $<$ 2.0 TeV$^{-2}$.

A new CMS tracker detector will be installed for operation at the High Luminosity LHC (HL-LHC). This detector comprises modules with two closely spaced parallel sensor plates and front-end ASICs capable of transmitting tracking information to the CMS Level-1 (L1) trigger at the 40 MHz beam crossing rate. The inclusion of tracking information in the L1 trigger decision will be essential for selecting events of interest efficiently at the HL-LHC. The CMS Binary Chip (CBC) has been designed to read out and correlate hits from pairs of tracker sensors, forming so-called track stubs. For the first time, a prototype irradiated module and a full-sized module, both equipped with the version 2 of the CBC, have been operated in test beam facilities. The efficiency of the stub finding logic of the modules for various angles of incidence has been studied. The ability of the modules to reject tracks with transverse momentum less than 2 GeV has been demonstrated. For modules built with irradiated sensors, no significant drop in the stub finding performance has been observed. Results from the beam tests are described in this paper.

Heavy ion collisions are used to study fundamental features of quantum chromodynamics (QCD) matter via its excitation to phases where quarks and gluons are no more confined into hadrons.Studies of the properties of this deconfined quark-gluon matter, called quark-gluon plasma (QGP), at the Brookhaven Relativistic Heavy-Ion Collider and the LHC have shown that the QGP behaves like a liquid with very small specific shear and bulk viscosities, and high opacity for energetic jets.Macroscopic (microscopic) properties are encoded in the collective expansion (underlying parton dynamics) of the strongly interacting QGP.Here, we review recent progress on measurements at the LHC particle production from small to large transverse momentum or mass, jet-induced medium response, heavy quark and exotic meson production, and photon-initiated processes.Increasingly high-precision data, along with novel approaches, offer stringent constraints on initial state, QGP formation and transport parameters, and even parametrizations beyond the standard model.

The Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and arranged into 16 "telescopes", with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run 2 (2015-18) of the LHC, as well as preparations for Run 3, which will begin in 2022.

For the first time, a search for the rare decay of the W boson to three charged pions has been performed. Proton-proton collision data recorded by the CMS experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 77.3 fb^{-1}, have been analyzed. No significant excess is observed above the background expectation. An upper limit of 1.01×10^{-6} is set at 95% confidence level on the branching fraction of the W boson to three charged pions. This provides a strong motivation for theoretical calculations of this branching fraction.

Central exclusive and semiexclusive production of $\pi^+\pi^-$ pairs is measured with the CMS detector in proton-proton collisions at the LHC at center-of-mass energies of 5.02 and 13 TeV. The theoretical description of these nonperturbative processes, which have not yet been measured in detail at the LHC, poses a significant challenge to models. The two pions are measured and identified in the CMS silicon tracker based on specific energy loss, whereas the absence of other particles is ensured by calorimeter information. The total and differential cross sections of exclusive and semiexclusive central $\pi^+\pi^-$ production are measured as functions of invariant mass, transverse momentum, and rapidity of the $\pi^+\pi^-$ system in the fiducial region defined as transverse momentum $p_\mathrm{T}(\pi)$ $>$ 0.2 GeV and pseudorapidity $|\eta(\pi)|$ $<$ 2.4. The production cross sections for the four resonant channels f$_0(500)$, $\rho^0(770)$, f$_0(980)$, and f$_2(1270)$ are extracted using a simple model. These results represent the first measurement of this process at the LHC collision energies of 5.02 and 13 TeV.

During the high-luminosity phase of the LHC (HL-LHC), planned to start in 2027, the accelerator is expected to deliver an instantaneous peak luminosity of up to 7.5×1034 cm−2 s−1. A total integrated luminosity of 0300 or even 0400 fb−1 is foreseen to be delivered to the general purpose detectors ATLAS and CMS over a decade, thereby increasing the discovery potential of the LHC experiments significantly. The CMS detector will undergo a major upgrade for the HL-LHC, with entirely new tracking detectors consisting of an Outer Tracker and Inner Tracker. However, the new tracking system will be exposed to a significantly higher radiation than the current tracker, requiring new radiation-hard sensors. CMS initiated an extensive irradiation and measurement campaign starting in 2009 to systematically compare the properties of different silicon materials and design choices for the Outer Tracker sensors. Several test structures and sensors were designed and implemented on 18 different combinations of wafer materials, thicknesses, and production technologies. The devices were electrically characterized before and after irradiation with neutrons, and with protons of different energies, with fluences corresponding to those expected at different radii of the CMS Outer Tracker after 0300 fb−1. The tests performed include studies with β sources, lasers, and beam scans. This paper compares the performance of different options for the HL-LHC silicon sensors with a focus on silicon bulk material and thickness.

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment’s silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to $$\Phi _{eq} = 2 \times 10^{16}$$ cm $$^{-2}$$ , and an ionising dose of $${\approx } 5$$ MGy after an integrated luminosity of 3000 fb $$^{-1}$$ . Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 $$\upmu $$ m thick p-bulk pad diodes and strip sensors irradiated up to fluences of $$\Phi _{eq} = 1.3 \times 10^{16}$$ cm $$^{-2}$$ are shown.

A new CMS Tracker is under development for operation at the High Luminosity LHC from 2026 onwards. It includes an outer tracker based on dedicated modules that will reconstruct short track segments, called stubs, using spatially coincident clusters in two closely spaced silicon sensor layers. These modules allow the rejection of low transverse momentum track hits and reduce the data volume before transmission to the first level trigger. The inclusion of tracking information in the trigger decision is essential to limit the first level trigger accept rate. A customized front-end readout chip, the CMS Binary Chip (CBC), containing stub finding logic has been designed for this purpose. A prototype module, equipped with the CBC chip, has been constructed and operated for the first time in a 4 GeV/c positron beam at DESY. The behaviour of the stub finding was studied for different angles of beam incidence on a module, which allows an estimate of the sensitivity to transverse momentum within the future CMS detector. A sharp transverse momentum threshold around 2 GeV/c was demonstrated, which meets the requirement to reject a large fraction of low momentum tracks present in the LHC environment on-detector. This is the first realistic demonstration of a silicon tracking module that is able to select data, based on the particle's transverse momentum, for use in a first level trigger at the LHC . The results from this test are described here.

In 2017 a new pixel detector was installed in the CMS detector. This so-called Phase-1 pixel detector features four barrel layers in the central region and three disks per end in the forward regions. The upgraded pixel detector requires an upgraded data acquisition (DAQ) system to accept a new data format and larger event sizes. A new DAQ and control system has been developed based on a combination of custom and commercial microTCA parts. Custom mezzanine cards on standard carrier cards provide a front-end driver for readout, and two types of front-end controller for configuration and the distribution of clock and trigger signals. Before the installation of the detector the DAQ system underwent a series of integration tests, including readout of the pilot pixel detector, which was constructed with prototype Phase-1 electronics and operated in CMS from 2015 to 2016, quality assurance of the CMS Phase-1 detector during its assembly, and testing with the CMS Central DAQ. This paper describes the Phase-1 pixel DAQ and control system, along with the integration tests and results. A description of the operational experience and performance in data taking is included.

We report the observation of the photon-induced γγ → τ + τ − production based on a data sample of 404 μ b −1 collected by the CMS experiment at a per nucleon center-of-mass energy of 5.02 TeV. The cross section is measured in a fiducial phase space region via the decay process involving one muon and three charged hadrons, and is found to be σ (γγ → τ + τ − ) = 4.8 ± 0.6 (stat) ± 0.5 (syst) μ b, in agreement with leading-order quantum electrodynamics predictions. The σ (γγ → τ + τ − ) measurement is used to determine the anomalous magnetic moment of the τ lepton a τ , which is currently poorly constrained.

Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the temperature dependence of the transport properties of quark-gluon plasma, the phase diagram of nuclear matter, the interaction of quarks and gluons at different scales and much more. This document, as part of the 2023 nuclear science long range planning process, was written to review the progress in hot QCD since the 2015 Long Range Plan for Nuclear Science, as well as highlight the realization of previous recommendations, and present opportunities for the next decade, building on the accomplishments and investments made in theoretical developments and the construction of new detectors. Furthermore, this document provides additional context to support the recommendations voted on at the Joint Hot and Cold QCD Town Hall Meeting, which are reported in a separate document.

The future opportunities for high-density QCD studies with ion and proton beams at the LHC are presented. Four major scientific goals are identified: the characterisation of the macroscopic long wavelength Quark-Gluon Plasma (QGP) properties with unprecedented precision, the investigation of the microscopic parton dynamics underlying QGP properties, the development of a unified picture of particle production and QCD dynamics from small (pp) to large (nucleus--nucleus) systems, the exploration of parton densities in nuclei in a broad ($x$, $Q^2$) kinematic range and the search for the possible onset of parton saturation. In order to address these scientific goals, high-luminosity Pb-Pb and p-Pb programmes are considered as priorities for Runs 3 and 4, complemented by high-multiplicity studies in pp collisions and a short run with oxygen ions. High-luminosity runs with intermediate-mass nuclei, for example Ar or Kr, are considered as an appealing case for extending the heavy-ion programme at the LHC beyond Run 4. The potential of the High-Energy LHC to probe QCD matter with newly-available observables, at twice larger center-of-mass energies than the LHC, is investigated.

To meet the increasing need for protein-rich food of an ever growing population, plant-based proteins are being utilized in meat products as replacements for animal-based proteins. Legumes such as soy can serve as an alternative protein source, by featuring both high protein content (36%) and protein functionality (gelation). Nowadays various meat replacement products are commercially available and thus more and more customers are willing to switch their diet to a vegetable-based one. Currently, the most efficient technology for the production of meat replacers is extrusion cooking and new methods of protein structuring (Shear Cell and Couette Cell) have only recently been introduced. These two new technologies were developed based on the principle of applying simple shear flow and heat in the protein mixture. Initially, a device called the Shear Cell was developed featuring a cone-cone design that could structure soy-based mixtures in meat-like products. However, since the Shear Cell design is limited to lab use only, a new technology was developed and presented in this thesis. The Couette Cell concept, which is based on the concentric cylinder principle, has been studied, since it allows for further upscaling at industrially relevant production volumes. The research starts with a proof of concept study by using the lab scaled Couette Cell, which features a volume of 0.14 L and a shearing zone gap size of 5 mm, between the two cylinders (Chapter 2). Applying simple shear and heat at varying process conditions (temperature, time and rotation rate) to a soy-based mixture, has yielded anisotropic structures that resembled meat. In particular, fibrous structures were favoured at temperatures between 90 and 100 °C. The fibrous products with the highest anisotropy indices were further examined and characterized with a set of complementary techniques (Chapter 3). With light microscopy we could observe structure formation over the visible surfaces of the specimens and by using a stain we could distinguish between the different ingredients. According to the texture analysis results, the anisotropy indices of the obtained meat replacer and raw meat (beef) are comparable. We introduced the use of neutron refraction method by utilizing spin-echo small angle neutron scattering (SESANS) to provide a look inside the bulk of the anisotropic meat replacer. It was therefore possible to quantify the number of fibre layers and the orientation distribution of the fibres present inside the specimens. The calculated fibre thickness was in line with the observations obtained with scanning electron microscopy (SEM). Since the Couette Cell concept proved successful and enabled scalable operation, we developed a new up-scaled Couette Cell, which can treat 7 L per batch, 50 times more than the lab-scaled Couette Cell. The detailed design of the up-scaled Couette Cell is discussed in Chapter 4. The up-scaled device allows for production of fibrous meat replacers at industrially relevant scales and opens the possibility of commercial production in an emerging market. The device is comprised of two concentric cylinders with the inner cylinder rotating while both are being heated by means of steam. The unique characteristic feature of the up-scaled Couette Cell is its 30 mm gap size, which is 6 times more than the lab-scaled counterpart. Finally, a parametric study was used to find the optimum process conditions between the process time and rotation rate while maintaining a constant temperature (Chapter 5). This study yielded highly fibrous structures with a characteristic 30 mm thickness, which emulates meat accurately. The Couette Cell concept and the flexibility in its design allow production of meat replacers at proportions currently not available. Additionally, no barriers were found for further upscaling this concept by preferably designing a continuous process.

This note represents an attempt to gather the input related to light-by-light scattering ($\gamma\gamma$) cross-section measurements at LHC with the aim of checking the consistency with different standard model predictions. For the first time, we also consider the contribution from the $\eta_b(1S)$ meson production to the diphoton invariant mass distribution, by calculating its inclusive photoproduction cross-section. Using a simplified set of assumptions, we find a result of $115\pm 19\,\,\text{nb}$, consistent with standard model predictions within two standard deviations. Although an improved determination of the integrated fiducial $\textrm{PbPb}\,(\gamma\gamma)\to \textrm{Pb}^{(\ast)}\textrm{+}\textrm{Pb}^{(\ast)}\,\gamma\gamma$ cross-section by approximately 10\% could be potentially achieved relative to current measurements, further improvements are expected with the inclusion of existing or forthcoming LHC nuclear data.

The multi-TeV energies available at LHC have opened up the possibility to measure, for the first time, various large-mass elementary particles in nuclear collisions. The current study presents the first observation of top quark--the heaviest elementary particle in the standard model--using proton-lead collisions. The measurement is based on a data set whose integrated luminosity amounts to 174 nb$^{-1}$, as recorded by CMS at a center-of-mass energy per nucleon pair of 8.16 TeV. The pair production process is measured using events with exactly one isolated lepton, electron or muon, and at least four jets, leading to a cross section of $45\pm8\ \rm{nb}$. This is well compatible with theoretical predictions from perturbative quantum chromodynamics at next-to-next-to-leading order with soft gluon resummation at next-to-next-to-leading logarithmic accuracy. The statistical significance of the signal against the background-only hypothesis is above five standard deviations.

Abstract We report measurement of elliptic flow \upsilon_{2}(p_{T}) in extended transverse momentum range for the identified cases of K_{s}^{0} (<8.5 GeV/c), \Lambda and \bar{\Lambda} (<7.5 GeV/c) in Pb- Pb 20-40% central collisions at \sqrt{s_{NN}}= 2.76 TeV measured with the ALICE detector at LHC. While K_{s}^{0} 's reach a maximum of \upsilon_{2}=0.167\pm0.0007(stat) at p_{T}\approx3 Gev/c, the baryon (anti-baryon) \upsilon_{2}(p_{T}) continues to rise until it reaches a maximum of \upsilon_{2}(p_{T})=0.213\pm0.0013(stat) \left(0.214\pm0.0014(stat)\right) at p_{T}\approx4 GeV/c. For larger p_{T} , the \upsilon_{2}(p_{T}) values exhibit a gradual decrease for all three cases. Quark scaling properties are also examined, indicating that at intermediate and high p_{T} scaling does not hold for strange particles \upsilon_{2}(p_{T}) .

The first measurement of the top quark pair production cross section ($\sigma_{\rm{t}\bar{\rm{t}}}$) in proton-proton collisions at $\sqrt{s} = 5.02$ TeV is reviewed. The data have been collected by the CMS experiment at the LHC and analyzed considering events with at least one charged lepton. The extraction of $\sigma_{\rm{t}\bar{\rm{t}}}$ can be used to constrain the gluon distribution function (PDF) at large longitudinal parton momentum fraction and to establish experimentally the relation between the top-quark mass as implemented in Monte-Carlo generators and the Lagrangian mass parameter. The impact of the measurement on the determination of the gluon PDF is illustrated through a quantum chromodynamic analysis at next-to-next-to-leading order and the result is furthermore put in context with other top quark measurements in different phase space regions. The measurement has paved the way for the first observation of top quark production in nuclear collisions and the subsequent study of modifications induced on the bound gluon PDF.

Precision measurement of the cross section for single top production is an important test of the Standard Model (SM). The purity of the collected data in single top events is limited by the understanding of the shape and yield of background contributions. Besides electroweak and $\rm{t\bar{t}}$ processes, QCD multijet events constitute a non-negligible background for the considered signal bq$'\rightarrow$ tq ($\textit{t}$-channel) process. The data-driven technique for constraining QCD contribution, employed in the measurement of the $\textit{t}$-channel single top-quark cross section using the very first LHC proton-proton collisions at $\sqrt{s}=13\ TeV$ with the CMS detector, is described. The dataset corresponds to an integrated luminosity of $\mathcal{L}=42\ pb^{\mathrm{-1}}$.

The top quark, being the heaviest elementary fermion known in the Standard model, has the largest coupling to the Higgs boson. The associated production of top quarks with the Higgs boson, either in pairs (t$\bar{\rm{t}}$H) or singly (tH), provides direct experimental access to the top-Higgs coupling $y_{\rm{t}}$. The t$\bar{\rm{t}}$H (tH) production mode, while proceeding at a rate of about 100 (1000) times smaller than gluon fusion, bears a highly distinctive experimental signature, which includes leptons and/or jets from the decay of the two (single) top quarks. The latest results of ttH searches at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of up to $35.9 \rm{fb}^{-1}$ as collected from CMS are shown and tantalizing evidence is found for measuring this crucial process with sufficient precision. However, higher precision data set is needed in order to confirm or disprove the previous observed excess. Initial searches for tH production mode at a center-of-mass energy of 13 TeV achieve comparable sensitivity to that of the Run 1 analysis.

The top quark, being the heaviest elementary fermion known in the Standard model, has the largest coupling to the Higgs boson.The associated production of top quarks with the Higgs boson, either in pairs (t tH) or singly (tH), provides direct experimental access to the top-Higgs coupling y t .The t tH (tH) production mode, while proceeding at a rate of about 100 (1000) times smaller than gluon fusion, bears a highly distinctive experimental signature, which includes leptons and/or jets from the decay of the two (single) top quarks.The latest results of ttH searches at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of up to 35.9 fb -1 as collected from CMS are shown and tantalizing evidence is found for measuring this crucial process with sufficient precision.However, higher precision data set is needed in order to confirm or disprove the previous observed excess.Initial searches for tH production mode at a center-ofmass energy of 13 TeV achieve comparable sensitivity to that of the Run 1 analysis.

The top quark, being the heaviest elementary fermion known in the Standard model, has the largest coupling to the Higgs boson. The associated production of top quarks with the Higgs boson, either in pairs (t$\bar{\rm{t}}$H) or singly (tH), provides direct experimental access to the top-Higgs coupling $y_{\rm{t}}$. The t$\bar{\rm{t}}$H (tH) production mode, while proceeding at a rate of about 100 (1000) times smaller than gluon fusion, bears a highly distinctive experimental signature, which includes leptons and/or jets from the decay of the two (single) top quarks. The latest results of ttH searches at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of up to $35.9\ \rm{fb}^{-1}$ as collected from CMS are shown and tantalizing evidence is found for measuring this crucial process with sufficient precision. However, higher precision data set is needed in order to confirm or disprove the previous observed excess. Initial searches for tH production mode at a center-of-mass energy of 13 TeV achieve comparable sensitivity to that of the Run 1 analysis.

The first measurement of the top quark pair production cross section ($\sigma_{\rm{t}\bar{\rm{t}}}$) in proton-proton collisions at $\sqrt{s} = 5.02$ TeV is reviewed. The data have been collected by the CMS experiment at the LHC and analyzed considering events with at least one charged lepton. The extraction of $\sigma_{\rm{t}\bar{\rm{t}}}$ can be used to constrain the gluon distribution function (PDF) at large longitudinal parton momentum fraction and to establish experimentally the relation between the top-quark mass as implemented in Monte-Carlo generators and the Lagrangian mass parameter. The impact of the measurement on the determination of the gluon PDF is illustrated through a quantum chromodynamic analysis at next-to-next-to-leading order and the result is furthermore put in context with other top quark measurements in different phase space regions. The measurement has paved the way for the first observation of top quark production in nuclear collisions and the subsequent study of modifications induced on the bound gluon PDF.

In this paper we report on the current status of studies on the expected performance for a detector designed to operate in a muon collider environment. Beam-induced backgrounds (BIB) represent the main challenge in the design of the detector and the event reconstruction algorithms. The current detector design aims to show that satisfactory performance can be achieved, while further optimizations are expected to significantly improve the overall performance. We present the characterization of the expected beam-induced background, describe the detector design and software used for detailed event simulations taking into account BIB effects. The expected performance of charged-particle reconstruction, jets, electrons, photons and muons is discussed, including an initial study on heavy-flavor jet tagging. A simple method to measure the delivered luminosity is also described. Overall, the proposed design and reconstruction algorithms can successfully reconstruct the high transverse-momentum objects needed to carry out a broad physics program.

The heavy ion (HI) program at the LHC has proven to be a successful and indispensable part of the LHC physics program. Its chief aim had been the detailed characterization of the quark-gluon plasma (QGP) in lead-lead collisions. Using additional data sets of proton-lead, proton-proton, and xenon-xenon collisions, the program has also included many advances, for example, in the understanding of the partonic nuclear structure, collectivity in smaller collision systems, and electromagnetic interactions. This Letter of Interest outlines the CMS Heavy Ion Group point of view regarding the scientific case for the use of ultrarelativistic HI beams in the coming decade to characterize QGP with unparalleled precision and to probe novel fundamental physics phenomena. More specifically, it outlines the open questions in the field which can be addressed with CMS, and aims to promote engagement from the US community and its international partners by building upon the recently concluded Snowmass 2022 exercise, the input provided to the European Strategy for Particle Physics, and proposed continuations and extensions of the last version of the US Long-Range Plan for Nuclear Physics.

The purpose of the Low-$x$ Workshop series is to stimulate discussions between experimentalists and theorists in diffractive hadronic physics, QCD dynamics at low $x$, parton saturation, and exciting problems in QCD at HERA, Tevatron, LHC, RHIC, and the future EIC. The central topics of the workshop, summarized in the current Proceedings, were: Diffraction in ep and e-ion collisions (including EIC physics); Diffraction and photon-exchange in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions; Spin Physics; Low-$x$ PDFs, forward physics, and hadronic final states. This Workshop has been the XXVIII edition in the series of the workshop.

After the discovery of the top quark more than 20 years ago, top quark production cross sections have been meticulously studied. The rich variety of results from the LHC experiments are complemented with increasingly accurate theoretical predictions of heavy quark production and decay. Measurements of the top quark production provide a benchmark test of perturbative quantum chromodynamics and the standard model (SM), constraining at the same time the background in Higgs boson searches as well as extensions beyond the SM. Recent top quark measurements from CMS are reviewed, illustrating past and current experimental methods along with their attained precision. A perspective of top quark physics at the High-Luminosity LHC and at future colliders is briefly given.

Using $1.7 \pm 0.1\,\mathrm{nb^{-1}}$ of lead-lead ($A = 208$) collision data recorded by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV, we report evidence of top quark pair ($\mathrm{t\bar{t}}$) production. The $\mathrm{t\bar{t}}$ cross section ($\sigma_\mathrm{t\bar{t}}$) is extracted from likelihood fits to a multivariate discriminator using lepton kinematic variables in dilepton final states and two methods. One method relies on the leptonic information alone, and the second one exploits, in addition, the presence of bottom quarks. The measured $\sigma_\mathrm{t\bar{t}}$ is $2.54^{+0.84}_{-0.74}$ and $2.03^{+0.71}_{-0.64}\, \mu\mathrm{b}$ in the two cases, respectively, consistent with predictions from perturbative quantum chromodynamics. We demonstrate, for the first time, that top quark decay products (leptonically decaying W bosons and bottom quarks) can be identified, irrespective of any possible final-state interactions with the quark-gluon plasma.

Ultrarelativistic heavy ion collisions at the laboratory provide a unique chance to study quantum chromodynamics (QCD) under extreme temperature (${\approx}150\,\mathrm{MeV}$) and density (${\approx}1\,\mathrm{GeV}/\mathrm{fm}^3$) conditions. Over the past decade, experimental results from LHC have shown further evidence for the formation of the quark-gluon plasma (QGP), a phase that is thought to permeate the early Universe and is formed in the high-density neutron-star cores. Various QCD predictions that model the behavior of the low-$x$ gluon nuclear density, a poorly explored region, are also tested. Since the photon flux per ion scales as the square of the emitting electric charge $Z^2$, cross sections of so far elusive photon-induced processes are extremely enhanced as compared to nucleon-nucleon collisions. Here, we review recent progress on CMS measurements of particle production with large transverse momentum or mass, photon-initiated processes, jet-induced medium response, and heavy quark production. These high-precision data, along with novel approaches, offer stringent constraints on initial state, QGP formation and transport parameters, and even parametrizations beyond the standard model.

Using $1.7 \pm 0.1\,\mathrm{nb^{-1}}$ of lead-lead ($A = 208$) collision data recorded by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV, we report evidence of top quark pair ($\mathrm{t\bar{t}}$) production. The $\mathrm{t\bar{t}}$ cross section ($\sigma_\mathrm{t\bar{t}}$) is extracted from likelihood fits to a multivariate discriminator using lepton kinematic variables in dilepton final states and two methods. One method relies on the leptonic information alone, and the second one exploits, in addition, the presence of bottom quarks. The measured $\sigma_\mathrm{t\bar{t}}$ is $2.54^{+0.84}_{-0.74}$ and $2.03^{+0.71}_{-0.64}\, \mu\mathrm{b}$ in the two cases, respectively, consistent with predictions from perturbative quantum chromodynamics. We demonstrate, for the first time, that top quark decay products (leptonically decaying W bosons and bottom quarks) can be identified, irrespective of any possible final-state interactions with the quark-gluon plasma.

Ultrarelativistic heavy ion collisions at the laboratory provide a unique chance to study quantum chromodynamics (QCD) under extreme temperature (${\approx}150\,\mathrm{MeV}$) and density (${\approx}1\,\mathrm{GeV}/\mathrm{fm}^3$) conditions. Over the past decade, experimental results from LHC have shown further evidence for the formation of the quark-gluon plasma (QGP), a phase that is thought to permeate the early Universe and is formed in the high-density neutron-star cores. Various QCD predictions that model the behavior of the low-$x$ gluon nuclear density, a poorly explored region, are also tested. Since the photon flux per ion scales as the square of the emitting electric charge $Z^2$, cross sections of so far elusive photon-induced processes are extremely enhanced as compared to nucleon-nucleon collisions. Here, we review recent progress on CMS measurements of particle production with large transverse momentum or mass, photon-initiated processes, jet-induced medium response, and heavy quark production. These high-precision data, along with novel approaches, offer stringent constraints on initial state, QGP formation and transport parameters, and even parametrizations beyond the standard model.

Droplets of quark-gluon plasma (QGP), an exotic state of strongly interacting quantum chromodynamics (QCD) matter, are routinely produced in heavy nuclei high-energy collisions. Although the experimental signatures marked a paradigm shift away from expectations of a weakly coupled QGP, a challenge remains as to how the locally deconfined state with a lifetime of a few fm can be resolved. The only colored particle that decays mostly within the QGP is the top quark. Here we demonstrate, for the first time, that top quark decay products are identified, irrespective of whether interacting with the medium (bottom quarks) or not (leptonically decaying W bosons). Using 1.7±0.1 nb−1 of lead-lead (A = 208) collision data recorded by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV, we report evidence of top quark pair (tt¯) production. Dilepton final states are selected, and the cross section (σtt¯) is measured from a likelihood fit to a multivariate discriminator using lepton kinematic variables. The σtt¯ measurement is additionally performed considering the jets originating from the hadronization of bottom quarks, which improve the sensitivity to the tt¯ signal process. After background subtraction and analysis corrections, the measured σtt¯ is 2.56 ± 0.82(tot) and 2.02 ± 0.69(tot)μb in the two cases, respectively, consistent with predictions from perturbative QCD.

How can we gain a detailed insight into the hydrodynamic response of the system created in heavy ion collisions to the fluctuating initial geometry and viscous effects? Do we create a strongly interacting medium in proton-nucleus and proton-proton collisions, or rather a system of partons undergoing few scatterings? To what extent can we discriminate between initial momentum correlations and flow generated as a response to the initial geometry via interactions in the final state? Do measurements of identified particle flow confirm the observations from inclusive charged hadrons? An experimental overview of anisotropic flow measurements, ranging from large down to the smallest collision systems, is given in these proceedings.

Using 1.7 ± 0.1 nb -1 of lead-lead ( = 208) collision data recorded by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV, we report evidence of top quark pair (tt ) production.The tt cross section ( tt ) is extracted from likelihood fits to a multivariate discriminator using lepton kinematic variables in dilepton final states and two methods.One method relies on the leptonic information alone, and the second one exploits, in addition, the presence of bottom quarks.The measured tt is 2.54 +0.84 -0.74 and 2.03 +0.71 -0.64 b in the two cases, respectively, consistent with predictions from perturbative quantum chromodynamics.We demonstrate, for the first time, that top quark decay products (leptonically decaying W bosons and bottom quarks) can be identified, irrespective of any possible final-state interactions with the quark-gluon plasma.

The presence of correlations between particles significantly separated in pseudorapidity in proton-proton and proton-nucleus collisions revealed surprises in the early LHC data. Are the physical processes responsible for the observed long-range pseudorapidity correlations and their azimuthal structure the same in small collision systems as in heavy ion collisions? Whereas in the case of heavy ion collisions is interpreted as generated by initial geometric inhomogeneities, calculations indicate that initial-state momentum correlations are present and could contribute to the observed azimuthal anisotropy in small systems. Probes involving heavy quarks provide us with a unique opportunity to disentangle different quantum chromodynamics effects at the boundary between low- and high-$p_{\mathrm{T}}$ interactions, and hence shed light on the origin of flow in small collision systems. A selection of the latest measurements is presented for the flow and production of heavy flavor hadrons and their decay products.

The presence of correlations between particles significantly separated in pseudorapidity in protonproton and proton-nucleus collisions revealed surprises in the early LHC data.Are the physical processes responsible for the observed long-range pseudorapidity correlations and their azimuthal structure the same in small collision systems as in heavy ion collisions?Whereas in the case of heavy ion collisions "flow" is interpreted as generated by initial geometric inhomogeneities, calculations indicate that initial-state momentum correlations are present and could contribute to the observed azimuthal anisotropy in small systems.Probes involving heavy quarks provide us with a unique opportunity to disentangle different quantum chromodynamics effects at the boundary between low-and high-T interactions, and hence shed light on the origin of flow in small collision systems.A selection of the latest measurements is presented for the flow and production of heavy flavor hadrons and their decay products.

The presence of correlations between particles significantly separated in pseudorapidity in proton-proton and proton-nucleus collisions revealed surprises in the early LHC data. Are the physical processes responsible for the observed long-range pseudorapidity correlations and their azimuthal structure the same in small collision systems as in heavy ion collisions? Whereas in the case of heavy ion collisions "flow" is interpreted as generated by initial geometric inhomogeneities, calculations indicate that initial-state momentum correlations are present and could contribute to the observed azimuthal anisotropy in small systems. Probes involving heavy quarks provide us with a unique opportunity to disentangle different quantum chromodynamics effects at the boundary between low- and high-$p_{\mathrm{T}}$ interactions, and hence shed light on the origin of flow in small collision systems. A selection of the latest measurements is presented for the flow and production of heavy flavor hadrons and their decay products.