Somnath Choudhury

Notwithstanding decades of progress since Yukawa first developed a description of the force between nucleons in terms of meson exchange1, a full understanding of the strong interaction remains a considerable challenge in modern science. One remaining difficulty arises from the non-perturbative nature of the strong force, which leads to the phenomenon of quark confinement at distances on the order of the size of the proton. Here we show that, in relativistic heavy-ion collisions, in which quarks and gluons are set free over an extended volume, two species of produced vector (spin-1) mesons, namely ϕ and K*0, emerge with a surprising pattern of global spin alignment. In particular, the global spin alignment for ϕ is unexpectedly large, whereas that for K*0 is consistent with zero. The observed spin-alignment pattern and magnitude for ϕ cannot be explained by conventional mechanisms, whereas a model with a connection to strong force fields2–6, that is, an effective proxy description within the standard model and quantum chromodynamics, accommodates the current data. This connection, if fully established, will open a potential new avenue for studying the behaviour of strong force fields. At the Relativistic Heavy Ion Collider, observations of two meson species produced by heavy-ion collisions, ϕ and K*0, show surprising patterns of global spin alignment, being unexpectedly large and consistent with zero, respectively.

We report on the measurements of directed flow $v_1$ and elliptic flow $v_2$ for hadrons ($\pi^{\pm}$, $K^{\pm}$, $K_{S}^0$, $p$, $\phi$, $\Lambda$ and $\Xi^{-}$) from Au+Au collisions at $\sqrt{s_{NN}}$ = 3\,GeV and $v_{2}$ for ($\pi^{\pm}$, $K^{\pm}$, $p$ and $\overline{p}$) at 27 and 54.4\,GeV with the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3\,GeV the $v_{2}$ at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the $v_1$ slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative $v_2$ and positive $v_1$ slope at 3\,GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.

Using the entire Belle data sample of $980\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ collisions, we present the results of a study of excited ${\mathrm{\ensuremath{\Omega}}}_{c}$ charmed baryons in the decay mode ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}{K}^{\ensuremath{-}}$. We show confirmation of four of the five narrow states reported by the LHCb Collaboration: the ${\mathrm{\ensuremath{\Omega}}}_{c}(3000)$, ${\mathrm{\ensuremath{\Omega}}}_{c}(3050)$, ${\mathrm{\ensuremath{\Omega}}}_{c}(3066)$, and ${\mathrm{\ensuremath{\Omega}}}_{c}(3090)$.

A search for the flavor-changing neutral-current decay B^{+}→K^{+}νν[over ¯] is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb^{-1} collected at the ϒ(4S) resonance and a sample of 9 fb^{-1} collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B^{+}→K^{+}νν[over ¯] decay, but also the inclusive properties of the other B meson in the ϒ(4S)→BB[over ¯] event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B^{+}→K^{+}νν[over ¯] of 4.1×10^{-5} is set at the 90% confidence level.

We measure triangular flow relative to the reaction plane at 3 GeV center-of-mass energy in Au+Au collisions at the BNL Relativistic Heavy Ion Collider. A significant v3 signal for protons is observed, which increases for higher rapidity, higher transverse momentum, and more peripheral collisions. The triangular flow is essentially rapidity-odd with a slope at midrapidity, dv3/dy|(y=0), opposite in sign compared to the slope for directed flow. No significant v3 signal is observed for charged pions and kaons. Comparisons with models suggest that a mean field potential is required to describe these results, and that the triangular shape of the participant nucleons is the result of stopping and nuclear geometry.7 MoreReceived 21 September 2023Accepted 6 March 2024DOI:https://doi.org/10.1103/PhysRevC.109.044914©2024 American Physical SocietyPhysics Subject Headings (PhySH)Equations of state of nuclear matterResearch AreasNuclear structure & decaysNuclear matterEquations of state of nuclear matterResearch AreasCollective flowEquations of state of nuclear matterRelativistic heavy-ion collisionsTransport in heavy-ion collisionsNuclear Physics

We report on measurements of sequential ϒ suppression in Au+Au collisions at sqrt[s_{NN}]=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0%-60% centrality class, the nuclear modification factors (R_{AA}), which quantify the level of yield suppression in heavy-ion collisions compared to p+p collisions, for ϒ(1S) and ϒ(2S) are 0.40±0.03(stat)±0.03(sys)±0.09(norm) and 0.26±0.08(stat)±0.02(sys)±0.06(norm), respectively, while the upper limit of the ϒ(3S) R_{AA} is 0.17 at a 95% confidence level. This provides experimental evidence that the ϒ(3S) is significantly more suppressed than the ϒ(1S) at RHIC. The level of suppression for ϒ(1S) is comparable to that observed at the much higher collision energy at the Large Hadron Collider. These results point to the creation of a medium at RHIC whose temperature is sufficiently high to strongly suppress excited ϒ states.

Hadronic event shapes have been measured in proton-proton collisions at sqrt(s)=7 TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 inverse picobarns. Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production.

A measurement of the top-antitop production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the top-antitop signal from W+jets and QCD multijet background events. The measured cross section is 173 + 39 - 32 (stat. + syst.) pb, consistent with standard model expectations.

Using data recorded with the Belle detector, we observe a new excited hyperon, an $\Omega^{*-}$ candidate decaying into $\Xi^0K^-$ and $\Xi^-K^0_S$ with a mass of $2012.4\pm0.7\ {\rm (stat)\pm\ 0.6\ (\rm syst)}\ {\rm MeV}/c^2$ and a width of $\Gamma=6.4^{+2.5}_{-2.0}\ {\rm(stat)}\pm1.6\ {\rm(syst)}\ {\rm MeV}$. The $\Omega^{*-}$ is seen primarily in $\Upsilon(1S), \Upsilon(2S)$, and $\Upsilon(3S)$ decays.

We report the result for a search for the leptonic decay of B+→μ+νμ using the full Belle dataset of 711 fb−1 of integrated luminosity at the Υ(4S) resonance. In the Standard Model leptonic B-meson decays are helicity and Cabibbo-Kobayashi-Maskawa suppressed. To maximize sensitivity an inclusive tagging approach is used to reconstruct the second B meson produced in the collision. The directional information from this second B meson is used to boost the observed μ into the signal B-meson rest frame, in which the μ has a monochromatic momentum spectrum. Though its momentum is smeared by the experimental resolution, this technique improves the analysis sensitivity considerably. Analyzing the μ momentum spectrum in this frame we find B(B+→μ+νμ)=(5.3±2.0±0.9)×10−7 with a one-sided significance of 2.8 standard deviations over the background-only hypothesis. This translates to a frequentist upper limit of B(B+→μ+νμ)<8.6×10−7 at 90% confidence level. The experimental spectrum is then used to search for a massive sterile neutrino, B+→μ+N, but no evidence is observed for a sterile neutrino with a mass in a range of 0–1.5 GeV. The determined B+→μ+νμ branching fraction limit is further used to constrain the mass and coupling space of the type II and type III two-Higgs-doublet models.7 MoreReceived 10 November 2019Accepted 2 January 2020DOI:https://doi.org/10.1103/PhysRevD.101.032007Published 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.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDetermination of fundamental constantsElectroweak interactionExtensions of Higgs sectorLattice QCDLeptonic, semileptonic & radiative decaysQuark mixingPhysical SystemsHeavy neutrinosLeptonsMesonsNuclear Physics

In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at s=200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R=0.2−0.6 in the transverse momentum range 15<pT,jet<60 GeV/c. These studies show that, in the pT,jet range accessible at s=200 GeV and with increasing jet resolution parameter and jet transverse momentum, the zg distribution asymptotically converges to the DGLAP splitting kernel for a quark radiating a gluon. The groomed jet radius measurements reflect a momentum-dependent narrowing of the jet structure for jets of a given resolution parameter, i.e., the larger the pT,jet, the narrower the first splitting. For the first time, these fully corrected measurements are compared to Monte Carlo generators with leading order QCD matrix elements and leading log in the parton shower, and to state-of-the-art theoretical calculations at next-to-leading-log accuracy. We observe that PYTHIA 6 with parameters tuned to reproduce RHIC measurements is able to quantitatively describe data, whereas PYTHIA 8 and HERWIG 7, tuned to reproduce LHC data, are unable to provide a simultaneous description of both zg and Rg, resulting in opportunities for fine parameter tuning of these models for p+p collisions at RHIC energies. We also find that the theoretical calculations without non-perturbative corrections are able to qualitatively describe the trend in data for jets of large resolution parameters at high pT,jet, but fail at small jet resolution parameters and low jet transverse momenta.

Abstract From April to July 2018, a data sample at the peak energy of the <?CDATA $ \varUpsilon \left( {4{\rm{S}}} \right)$?> resonance was collected with the Belle II detector at the SuperKEKB electron-positron collider. This is the first data sample of the Belle II experiment. Using Bhabha and digamma events, we measure the integrated luminosity of the data sample to be ( <?CDATA $ 496.3 \pm 0.3 \pm 3.0)\;{\rm pb}^{-1}$?> , where the first uncertainty is statistical and the second is systematic. This work provides a basis for future luminosity measurements at Belle II.

We present measurements of partial branching fractions of inclusive semileptonic $B\ensuremath{\rightarrow}{X}_{u}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ decays using the full Belle dataset of $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance and for $\ensuremath{\ell}=e$, $\ensuremath{\mu}$. Inclusive semileptonic $B\ensuremath{\rightarrow}{X}_{u}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ decays are Cabibbo-Kobayashi-Maskawa (CKM) suppressed and measurements are complicated by the large background from CKM favored $B\ensuremath{\rightarrow}{X}_{c}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ transitions, which have a similar signature. Using machine learning techniques, we reduce this and other backgrounds effectively, while retaining access to a large fraction of the $B\ensuremath{\rightarrow}{X}_{u}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ phase space and high signal efficiency. We measure partial branching fractions in three phase-space regions covering about 31% to 86% of the accessible $B\ensuremath{\rightarrow}{X}_{u}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ phase space. The most inclusive measurement corresponds to the phase space with lepton energies of ${E}_{\ensuremath{\ell}}^{B}&gt;1\text{ }\text{ }\mathrm{GeV}$, and we obtain $\mathrm{\ensuremath{\Delta}}\mathcal{B}(B\ensuremath{\rightarrow}{X}_{u}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}})=(1.59\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.16)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ from a two-dimensional fit of the hadronic mass spectrum and the four-momentum-transfer squared distribution, with the uncertainties denoting the statistical and systematic error. We find $|{V}_{ub}|=(4.10\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.22\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ from an average of four calculations for the partial decay rate with the third uncertainty denoting the average theory error. This value is higher but compatible with the determination from exclusive semileptonic decays within 1.3 standard deviations. In addition, we report charmless inclusive partial branching fractions separately for ${B}^{+}$ and ${B}^{0}$ mesons as well as for electron and muon final states. No isospin breaking or lepton flavor universality violating effects are observed.

The authors present the best high-precision measurements of the longitudinal double-spin asymmetry for jet and dijet production in polarized proton collisions, improving on their previous results. The data are sensitive to the gluon helicity distribution and provide new constraints.

A two-dimensional steady-state model for a phosphoric acid fuel cell (PAFC) is developed. While most of the published literature deals with one-dimensional models for PAFC, a two-dimensional model is necessitated in cases where the oxygen concentration changes substantially in the flow direction due to depletion of oxygen and back diffusion of product water. The proposed modeling strategy was validated by: (i) testing in one-dimensional mode for verification of the basic parameters through a micro setup known as “unit cell”, and (ii) evaluation of the two-dimensional model through an experimental setup of a PAFC stack with four cells. Further, the utility of the model in design and humidity management, and parametric sensitivity studies are presented.

The modifications induced in the standard weak-lensing formula if Newtonian gravity differs from inverse square law at large distances are studied. The possibility of putting bounds on the mass of gravitons from lensing data is explored. A bound on graviton mass, esitmated to be about 100 Mpc$^{-1}$ is obtained from analysis of some recent data on gravitational lensing.

We present the measurement of the first to fourth order moments of the four-momentum transfer squared, q2, of inclusive B→Xcℓ+νℓ decays using the full Belle dataset of 711 fb−1 of integrated luminosity at the Υ(4S) resonance where ℓ=e, μ. The determination of these moments and their systematic uncertainties open new pathways to determine the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element Vcb using a reduced set of matrix elements of the heavy quark expansion. In order to identify and reconstruct the Xc system, we reconstruct one of the two B-mesons using machine learning techniques in fully hadronic decay modes. The moments are measured with progressively increasing threshold selections on q2 starting with a lower value of 3.0 GeV2 in steps of 0.5 GeV2 up to a value of 10.0 GeV2. The measured moments are further unfolded, correcting for reconstruction and selection effects as well as QED final state radiation. We report the moments separately for electron and muon final states and observe no lepton flavor universality violating effects.11 MoreReceived 7 September 2021Accepted 6 December 2021DOI:https://doi.org/10.1103/PhysRevD.104.112011Published 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.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasLeptonic, semileptonic & radiative decaysPhysical SystemsBottom quarkTechniquesParticle data analysisPrecision measurementsParticles & Fields

Understanding gluon density distributions and how they are modified in nuclei are among the most important goals in nuclear physics. In recent years, diffractive vector meson production measured in ultraperipheral collisions (UPCs) at heavy-ion colliders has provided a new tool for probing the gluon density. In this Letter, we report the first measurement of J/ψ photoproduction off the deuteron in UPCs at the center-of-mass energy sqrt[s_{NN}]=200 GeV in d+Au collisions. The differential cross section as a function of momentum transfer -t is measured. In addition, data with a neutron tagged in the deuteron-going zero-degree calorimeter is investigated for the first time, which is found to be consistent with the expectation of incoherent diffractive scattering at low momentum transfer. Theoretical predictions based on the color glass condensate saturation model and the leading twist approximation nuclear shadowing model are compared with the data quantitatively. A better agreement with the saturation model has been observed. With the current measurement, the results are found to be directly sensitive to the gluon density distribution of the deuteron and the deuteron breakup process, which provides insights into the nuclear gluonic structure.

We report measurements of the longitudinal double-spin asymmetry, ${A}_{LL}$, for inclusive jet and dijet production in polarized proton-proton collisions at midrapidity and center-of-mass energy $\sqrt{s}=510\text{ }\text{ }\mathrm{GeV}$, using the high luminosity data sample collected by the STAR experiment in 2013. These measurements complement and improve the precision of previous STAR measurements at the same center-of-mass energy that probe the polarized gluon distribution function at partonic momentum fraction $0.015\ensuremath{\lesssim}x\ensuremath{\lesssim}0.25$. The dijet asymmetries are separated into four jet-pair topologies, which provide further constraints on the $x$ dependence of the polarized gluon distribution function. These measurements are in agreement with previous STAR measurements and with predictions from current next-to-leading-order global analyses. They provide more precise data at low dijet invariant mass that will better constrain the shape of the polarized gluon distribution function of the proton.

Abstract The Compact Muon Solenoid collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glued between an electronics circuit board and a metal baseplate. The sensor pads of approximately 1.1 cm 2 are wire-bonded to the circuit board and are readout by custom integrated circuits. The prototype was extensively tested with beams at CERN's Super Proton Synchrotron in 2018. Based on the data collected with beams of positrons, with energies ranging from 20 to 300 GeV, measurements of the energy resolution and linearity, the position and angular resolutions, and the shower shapes are presented and compared to a detailed Geant4 simulation.

Azimuthal anisotropy of produced particles is one of the most important observables used to access the collective properties of the expanding medium created in relativistic heavy-ion collisions. In this paper, we present second (${v}_{2}$) and third (${v}_{3}$) order azimuthal anisotropies of ${K}_{S}^{0}, \ensuremath{\phi}, \mathrm{\ensuremath{\Lambda}}, \mathrm{\ensuremath{\Xi}}$, and $\mathrm{\ensuremath{\Omega}}$ at midrapidity ($|y|&lt;1$) in Au+Au collisions at $\sqrt{{s}_{NN}}=54.4$ GeV measured by the STAR detector. The ${v}_{2}$ and ${v}_{3}$ are measured as a function of transverse momentum and centrality. Their energy dependence is also studied. ${v}_{3}$ is found to be more sensitive to the change in the center-of-mass energy than ${v}_{2}$. Scaling by constituent quark number is found to hold for ${v}_{2}$ within 10%. This observation could be evidence for the development of partonic collectivity in 54.4 GeV Au+Au collisions. Differences in ${v}_{2}$ and ${v}_{3}$ between baryons and antibaryons are presented, and ratios of ${v}_{3}/{v}_{2}^{3/2}$ are studied and motivated by hydrodynamical calculations. The ratio of ${v}_{2}$ of $\ensuremath{\phi}$ mesons to that of antiprotons $[{v}_{2}(\ensuremath{\phi})/{v}_{2}(\overline{p})]$ shows centrality dependence at low transverse momentum, presumably resulting from the larger effects from hadronic interactions on antiproton ${v}_{2}$.

originating from the initial density fluctuations.The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild pT dependence.The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagree with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions.The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and pT dependence that still disagree with experimental measurements.Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization.Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.

We report a search for a heavy neutral lepton (HNL) that mixes predominantly with $\nu_\tau$. The search utilizes data collected with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. The data sample was collected at and just below the center-of-mass energies of the $\Upsilon(4S)$ and $\Upsilon(5S)$ resonances and has an integrated luminosity of $915~\textrm{fb}^{-1}$, corresponding to $(836\pm 12)\times 10^6$ $e^+e^\to\tau^+\tau^-$ events. We search for production of the HNL (denoted $N$) in the decay $\tau^-\to \pi^- N$ followed by its decay via $N \to \mu^+\mu^- \nu_\tau$. The search focuses on the parameter-space region in which the HNL is long lived, so that the $\mu^+\mu^-$ originate from a common vertex that is significantly displaced from the collision point of the KEKB beams. Consistent with the expected background yield, one event is observed in the data sample after application of all the event-selection criteria. We report limits on the mixing parameter of the HNL with the $\tau$ neutrino as a function of the HNL mass.

We present systematic measurements of azimuthal anisotropy for strange and multistrange hadrons (${K}_{s}^{0}, \mathrm{\ensuremath{\Lambda}}, \mathrm{\ensuremath{\Xi}}$, and $\mathrm{\ensuremath{\Omega}}$) and $\ensuremath{\phi}$ mesons at midrapidity ($|y|&lt;$ 1.0) in collisions of $\mathrm{U}+\mathrm{U}$ nuclei at $\sqrt{{s}_{NN}}=193$ GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. Transverse momentum (${p}_{T}$) dependence of flow coefficients (${v}_{2}, {v}_{3}$, and ${v}_{4}$) is presented for minimum bias collisions and three different centrality intervals. Number of constituent quark scaling of the measured flow coefficients in $\mathrm{U}+\mathrm{U}$ collisions is discussed. We also present the ratio of ${v}_{n}$ scaled by the participant eccentricity (${\ensuremath{\varepsilon}}_{n}\left\{2\right\}$) to explore system size dependence and collectivity in $\mathrm{U}+\mathrm{U}$ collisions. The magnitude of ${v}_{2}/{\ensuremath{\varepsilon}}_{2}$ is found to be smaller in $\mathrm{U}+\mathrm{U}$ collisions than that in central $\mathrm{Au}+\mathrm{Au}$ collisions contradicting naive eccentricity scaling. Furthermore, the ratios between various flow harmonics (${v}_{3}/{v}_{2}^{3/2}, {v}_{4}/{v}_{2}^{4/2}$) are studied and compared with hydrodynamic and transport model calculations.

The first measurements of differential branching fractions of inclusive semileptonic B→X_{u}ℓ^{+}ν_{ℓ} decays are performed using the full Belle data set of 711 fb^{-1} of integrated luminosity at the ϒ(4S) resonance and for ℓ=e, μ. With the availability of these measurements, new avenues for future shape-function model-independent determinations of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}| can be pursued to gain new insights in the existing tension with respect to exclusive determinations. The differential branching fractions are reported as a function of the lepton energy, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic B→X_{c}ℓ^{+}ν_{ℓ} decays and other processes, and corrected for resolution and acceptance effects.

Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive J/ψ at mid-rapidity in 0-100% p+Au collisions at sNN = 200 GeV is presented. Such effects are quantified utilizing the nuclear modification factor, RpAu, obtained by taking a ratio of J/ψ yield in p+Au collisions to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The differential J/ψ yield in both p+p and p+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the J/ψ RpAu is derived within the transverse momentum (pT) range of 0 to 10 GeV/c. A suppression of approximately 30% is observed for pT<2 GeV/c, while J/ψ RpAu becomes compatible with unity for pT greater than 3 GeV/c, indicating the J/ψ yield is minimally affected by the CNM effects at high pT. Comparison to a similar measurement from 0-20% central Au+Au collisions reveals that the observed strong J/ψ suppression above 3 GeV/c is mostly due to the hot medium effects, providing strong evidence for the formation of the quark-gluon plasma in these collisions. Several model calculations show qualitative agreement with the measured J/ψ RpAu, while their agreement with the J/ψ yields in p+p and p+Au collisions is worse.

Transient state response analysis of phosphoric acid fuel cell (PAFC) cathode is important to understand various competitive processes like diffusion, reaction and product back diffusion occurring at various layers of the composite cathode. A two-dimensional unsteady state model for simulating PAFC cathode is developed as an extension of the previously developed steady-state model [S. Roy Choudhury, M.B. Deshmukh, R. Rengaswamy, A two-dimensional steady-state model for phosphoric acid fuel cells (PAFC), J. Power sources 112 (2002) 137–152]. The transient model is solved to study the impact of various parameters such as Tafel slope, diffusivity etc on the step response of the fuel cell. The effect of partial pressure variation in bulk gas for large sized PAFC cathode is also analysed. Trend analysis based on the model output is also experimentally verified using a small unit cell setup. The effect of various parameters on the settling time of the cathode, as revealed in this study, suggests possible development of a diagnostic tool employing such transient model.

Using a data sample of 980~fb$^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we present evidence for the $\Omega(2012)^-$ in the resonant substructure of $\Omega_{c}^{0} \to \pi^+ (\bar{K}\Xi)^{-}$ ($(\bar{K}\Xi)^{-}$ = $K^-\Xi^0$ + $\bar{K}^0 \Xi^-$) decays. The significance of the $\Omega(2012)^-$ signal is 4.2$\sigma$ after considering the systematic uncertainties. The ratio of the branching fraction of $\Omega_{c}^{0} \to \pi^{+} \Omega(2012)^- \to \pi^+ (\bar{K}\Xi)^{-}$ relative to that of $\Omega_{c}^{0} \to \pi^{+} \Omega^-$ is calculated to be 0.220 $\pm$ 0.059(stat.) $\pm$ 0.035(syst.). The individual ratios of the branching fractions of the two isospin modes are also determined, and found to be ${\cal B}(\Omega_{c}^0 \to \pi^+ \Omega(2012)^-) \times {\cal B}(\Omega(2012)^- \to K^-\Xi^0)/{\cal B}(\Omega_{c}^0 \to \pi^+ K^- \Xi^0)$ = (9.6 $\pm$ 3.2(stat.) $\pm$ 1.8(syst.))\% and ${\cal B}(\Omega_{c}^0 \to \pi^+ \Omega(2012)^-) \times {\cal B}(\Omega(2012)^- \to \bar{K}^0 \Xi^-)/{\cal B}(\Omega_{c}^0 \to \pi^+ \bar{K}^0 \Xi^-)$ = (5.5 $\pm$ 2.8(stat.) $\pm$ 0.7(syst.))\%.

In this note we examine the constraints imposed by muon anomalous magnetic moment ($(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$) and ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{e}^{\ensuremath{-}}$ on lepton number violating (LNV) couplings of the triplet Higgs in Little Higgs (LH) model.

This corrects the article DOI: 10.1103/PhysRevLett.126.162301.

Little Higgs models are often endowed with a T-parity in order to satisfy electroweak precision tests and give at the same time a stable particle which is a candidate for cold dark matter. This type of models predicts a set of new T-odd fermions in addition to the heavy gauge bosons of the Little Higgs models, which may show interesting signatures at colliders. In this paper, we study the signatures of strong and electroweak pair production of the first two generations of T-odd quarks at the LHC. We focus on the dileptonic signatures (a) pp → ℓ ± ℓ ∓ jj (opposite-sign dileptons) and (b) pp → ℓ ± ℓ ± jj (same-sign dileptons).

Recently proposed stabilization mechanism of the Randall-Sundrum metric gives rise to a scalar radion, which couples universally to matter with a weak interaction ($\simeq 1$ TeV) scale. Demanding that gauge boson scattering as described by the effective low enerrgy theory be unitary upto a given scale leads to significant constraints on the mass of such a radion.

We report the observation of ϒ(2S)→γη_{b}(1S) decay based on an analysis of the inclusive photon spectrum of 24.7 fb^{-1} of e^{+}e^{-} collisions at the ϒ(2S) center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure a branching fraction of B[ϒ(2S)→γη_{b}(1S)]=(6.1_{-0.7-0.6}^{+0.6+0.9})×10^{-4} and derive an η_{b}(1S) mass of 9394.8_{-3.1-2.7}^{+2.7+4.5} MeV/c^{2}, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.

We present the first inclusive measurements of the invariant and SoftDrop jet mass in proton-proton collisions at $\sqrt{s}=200$ GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned PYTHIA-6 reproduces the data, while LHC tunes of PYTHIA-8 and HERWIG-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that SoftDrop grooming, for which the contribution of wide-angle non-perturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both PYTHIA-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.

Searches for Beyond Standard Model (BSM) Higgs bosons at the CMS experiment are presented. The analyses are based on proton-proton collision data recorded by the CMS experiment at the LHC at CERN at 7 and 8 TeV centre-of-mass energies in the years 2011 and 2012 respectively, corresponding to an integrated luminosity of up to 25 fb $$^{-1}$$ . No evidence for additional Higgs bosons other than the 125 GeV standard model-like Higgs boson are found, and stringent exclusion limits are derived in different BSM scenarios.

In this note we study an interesting effect of low energy gravity on photon-photon scattering at high energies.

Global polarizations ($P$) of $\mathrm{\ensuremath{\Lambda}} (\overline{\mathrm{\ensuremath{\Lambda}}})$ hyperons have been observed in noncentral heavy-ion collisions. The strong magnetic field primarily created by the spectator protons in such collisions would split the $\mathrm{\ensuremath{\Lambda}}$ and $\overline{\mathrm{\ensuremath{\Lambda}}}$ global polarizations ($\mathrm{\ensuremath{\Delta}}P={P}_{\mathrm{\ensuremath{\Lambda}}}\ensuremath{-}{P}_{\overline{\mathrm{\ensuremath{\Lambda}}}}&lt;0$). Additionally, quantum chromodynamics predicts topological charge fluctuations in vacuum, resulting in a chirality imbalance or parity violation in a local domain. This would give rise to an imbalance ($\mathrm{\ensuremath{\Delta}}n=\frac{{N}_{\text{L}}\ensuremath{-}{N}_{\text{R}}}{\ensuremath{\langle}{N}_{\text{L}}+{N}_{\text{R}}\ensuremath{\rangle}}\ensuremath{\ne}0$) between left- and right-handed $\mathrm{\ensuremath{\Lambda}}$ ($\overline{\mathrm{\ensuremath{\Lambda}}}$) as well as a charge separation along the magnetic field, referred to as the chiral magnetic effect (CME). This charge separation can be characterized by the parity-even azimuthal correlator ($\mathrm{\ensuremath{\Delta}}\ensuremath{\gamma}$) and parity-odd azimuthal harmonic observable ($\mathrm{\ensuremath{\Delta}}{a}_{1}$). Measurements of $\mathrm{\ensuremath{\Delta}}P, \mathrm{\ensuremath{\Delta}}\ensuremath{\gamma}$, and $\mathrm{\ensuremath{\Delta}}{a}_{1}$ have not led to definitive conclusions concerning the CME or the magnetic field, and $\mathrm{\ensuremath{\Delta}}n$ has not been measured previously. Correlations among these observables may reveal new insights. This paper reports measurements of correlation between $\mathrm{\ensuremath{\Delta}}n$ and $\mathrm{\ensuremath{\Delta}}{a}_{1}$, which is sensitive to chirality fluctuations, and correlation between $\mathrm{\ensuremath{\Delta}}P$ and $\mathrm{\ensuremath{\Delta}}\ensuremath{\gamma}$ sensitive to magnetic field in $\mathrm{Au}+\mathrm{Au}$ collisions at 27 GeV. For both measurements, no correlations have been observed beyond statistical fluctuations.

In this paper we shall study the phenomenology of a doubly charged and neutral exchange black hole in an (n+3) extra-dimensional scenario, where the black hole shall be treated as a normal quantum field.

A bstract We measure the branching fractions and CP asymmetries for the singly Cabibbo-suppressed decays D 0 → π + π − η , D 0 → K + K − η , and D 0 → ϕη , using 980 fb − 1 of data from the Belle experiment at the KEKB e + e − collider. We obtain $$ {\displaystyle \begin{array}{c}\mathcal{B}\left({D}^0\to {\pi}^{+}{\pi}^{-}\eta \right)=\left[1.22\pm 0.02\left(\mathrm{stat}\right)\pm 0.02\left(\mathrm{syst}\right)\pm 0.03\left({\mathcal{B}}_{\mathrm{ref}}\right)\right]\times {10}^{-3},\\ {}\mathcal{B}\left({D}^0\to {K}^{+}{K}^{-}\eta \right)=\left[{1.80}_{-0.06}^{+0.07}\left(\mathrm{stat}\right)\pm 0.04\left(\mathrm{syst}\right)\pm 0.05\left({\mathcal{B}}_{\mathrm{ref}}\right)\right]\times {10}^{-4},\\ {}\mathcal{B}\left({D}^0\to \phi \eta \right)=\left[1.84\pm 0.09\left(\mathrm{stat}\right)\pm 0.06\left(\mathrm{syst}\right)\pm 0.05\left({\mathcal{B}}_{\mathrm{ref}}\right)\right]\times {10}^{-4},\end{array}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mtable> <mml:mtr> <mml:mtd> <mml:mi>B</mml:mi> <mml:mfenced> <mml:mrow> <mml:msup> <mml:mi>D</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:mi>η</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mrow> <mml:mn>1.22</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.02</mml:mn> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.02</mml:mn> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.03</mml:mn> <mml:mfenced> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>ref</mml:mi> </mml:msub> </mml:mfenced> </mml:mrow> </mml:mfenced> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> <mml:mo>,</mml:mo> </mml:mtd> </mml:mtr> <mml:mtr> <mml:mtd> <mml:mi>B</mml:mi> <mml:mfenced> <mml:mrow> <mml:msup> <mml:mi>D</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:mi>η</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mrow> <mml:msubsup> <mml:mn>1.80</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.06</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.07</mml:mn> </mml:mrow> </mml:msubsup> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.04</mml:mn> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.05</mml:mn> <mml:mfenced> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>ref</mml:mi> </mml:msub> </mml:mfenced> </mml:mrow> </mml:mfenced> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> </mml:msup> <mml:mo>,</mml:mo> </mml:mtd> </mml:mtr> <mml:mtr> <mml:mtd> <mml:mi>B</mml:mi> <mml:mfenced> <mml:mrow> <mml:msup> <mml:mi>D</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:mi>ϕη</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mrow> <mml:mn>1.84</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.09</mml:mn> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.06</mml:mn> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.05</mml:mn> <mml:mfenced> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>ref</mml:mi> </mml:msub> </mml:mfenced> </mml:mrow> </mml:mfenced> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> </mml:msup> <mml:mo>,</mml:mo> </mml:mtd> </mml:mtr> </mml:mtable> </mml:math> where the third uncertainty ( $$ \mathcal{B} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> </mml:math> ref ) is from the uncertainty in the branching fraction of the reference mode D 0 → K − π + η . The color-suppressed decay D 0 → ϕη is observed for the first time, with very high significance. The results for the CP asymmetries are $$ {\displaystyle \begin{array}{c}{A}_{CP}\left({D}^0\ {\pi}^{+}{\pi}^{-}\eta \right)=\left[0.9\pm 1.2\left(\mathrm{stat}\right)\pm 0.5\left(\mathrm{syst}\right)\right]\%,\\ {}{A}_{CP}\left({D}^0\to {K}^{+}{K}^{-}\eta \right)=\left[-1.4\pm 3.3\left(\mathrm{stat}\right)\pm 1.1\left(\mathrm{syst}\right)\right]\%,\\ {} ACP\ \left({D}^0\to \phi \eta \right)=\left[-1.9\pm 4.4\left(\mathrm{stat}\right)\pm 0.6\left(\mathrm{syst}\right)\right]\%.\end{array}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mtable> <mml:mtr> <mml:mtd> <mml:msub> <mml:mi>A</mml:mi> <mml:mi>CP</mml:mi> </mml:msub> <mml:mfenced> <mml:mrow> <mml:msup> <mml:mi>D</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mspace /> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:mi>η</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mrow> <mml:mn>0.9</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1.2</mml:mn> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.5</mml:mn> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> </mml:mrow> </mml:mfenced> <mml:mo>%</mml:mo> <mml:mo>,</mml:mo> </mml:mtd> </mml:mtr> <mml:mtr> <mml:mtd> <mml:msub> <mml:mi>A</mml:mi> <mml:mi>CP</mml:mi> </mml:msub> <mml:mfenced> <mml:mrow> <mml:msup> <mml:mi>D</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:mi>η</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.4</mml:mn> <mml:mo>±</mml:mo> <mml:mn>3.3</mml:mn> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>1.1</mml:mn> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> </mml:mrow> </mml:mfenced> <mml:mo>%</mml:mo> <mml:mo>,</mml:mo> </mml:mtd> </mml:mtr> <mml:mtr> <mml:mtd> <mml:mi>ACP</mml:mi> <mml:mspace /> <mml:mfenced> <mml:mrow> <mml:msup> <mml:mi>D</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:mi>ϕη</mml:mi> </mml:mrow> </mml:mfenced> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.9</mml:mn> <mml:mo>±</mml:mo> <mml:mn>4.4</mml:mn> <mml:mfenced> <mml:mtext>stat</mml:mtext> </mml:mfenced> <mml:mo>±</mml:mo> <mml:mn>0.6</mml:mn> <mml:mfenced> <mml:mtext>syst</mml:mtext> </mml:mfenced> </mml:mrow> </mml:mfenced> <mml:mo>%</mml:mo> <mml:mo>.</mml:mo> </mml:mtd> </mml:mtr> </mml:mtable> </mml:math> The results for D 0 → π + π − η are a significant improvement over previous results. The branching fraction and A CP results for D 0 → K + K − η , and the ACP result for D 0 → ϕη , are the first such measurements. No evidence for CP violation is found in any of these decays.

Abstract The CMS phase-1 pixel detector was designed to cope with an instantaneous luminosity of 2 × 10 34 cm −2 s −1 and 25 ns bunch spacing with very small efficiency loss. The upgraded detector has 124 million channels that features a 4-hit coverage in the tracking volume with an additional layer in the barrel and one extra disk in both the endcaps. DC-DC converters have been used to deliver more power to the detector without the need of replacing the cable plant. A CO 2 based cooling system was implemented and carbon fibre based support structures were used to reduce the material budget in the tracking volume. The data acquisition system was upgraded to cope with higher collision rates with a digital data format from the detector front-ends. The detector was installed in early 2017 and has been successfully operated since then. In this paper, the design and construction, operational experience and the performance of the phase-1 pixel detector at LHC Run 2 will be summarised.

The results on the observation of the Higgs boson in decays to bosons and fermions have been reported from the LHC and Tevatron. A direct evidence of the Higgs-lepton coupling is established at the LHC with the tau pair decay mode and a direct indication of Higgs boson coupling to fermions is observed in decays to bottom quarks at the Tevatron. The measurements of the Higgs boson mass, coupling to vector bosons and fermions, spin and parity, decay width and production cross section have been reported.

The results on the standard model Higgs boson in tau pair decay using 25 fb–1 of pp collision data at 7 and 8 TeV center-of-mass energies collected by the CMS detector at the LHC has been presented. A direct evidence of the Higgs-lepton coupling is established with the tau pair decay mode. Searches for Higgs bosons decaying to tau leptons in scenarios beyond the standard model such as supersymmetry within the minimal extension of the model has also been reported.

Black holes at the TeV scale are investigated in the extra large dimension scenario. We interpret the lightest black hole excitation as a singlet scalar field, and show how interaction terms can be appended to the standard model at the dimension five non-renormalizable level. Lepton family number violation is natural in this model. Muon magnetic moment, and neutrino masses are investigated. We also present a quantization scheme in n dimensions.

We examine the implications of the Randall-Sundrum gravity models on $\gamma\gamma$ scattering in the TeV range.

This paper has been withdrawn by the author due to a crucial technical error in the article.

The searches for light pseudoscalar Higgs bosons pair produced from the decay of the 125 GeV Higgs boson and resulting in various final states (4$\mu$, 2$\mu$2$\tau$, 2b2$\tau$) according to the mass of the light boson and searches for low mass scalar bosons below 125 GeV in decays to photon pairs will be summarised. The analyses are performed using data collected with the CMS experiment at the LHC from pp collisions at centre-of-mass energy of 13 TeV.

The enhancement of charged-particle pairs with large pseudorapidity difference and small azimuthal angle difference, often referred to as the ``ridge signal'', is a phenomenon widely observed in high multiplicity proton-proton, proton-ion and deutron-ion collisions, which is not yet fully understood. In heavy-ion collisions, the hydrodynamic expansion of the Quark-Gluon Plasma is one of the possible explanations of the origin of the ridge signal. Measurements in the $e^+e^-$ collision system, without the complexities introduced by hadron structure in the initial state, can serve as a complementary probe to examine the formation of a ridge signal. The first measurement of two-particle angular correlation functions in high multiplicity $e^+e^-$ collisions at $\sqrt{s}=10.52$ GeV is reported. The hadronic $e^+e^-$ annihilation data collected by the Belle detector at KEKB are used in this study. Two-particle angular correlation functions are measured over the full azimuth and large pseudorapidity intervals which are defined by either the electron beam axis or the event thrust as a function of charged particle multiplicity. The measurement in the event thrust analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant ridge signal is observed with either coordinates analyses. Near side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and expected to provide new constraints to the phenomenological models in the low energy regime.

We present measurements of the first six hadronic mass moments in semileptonic $B \rightarrow X_c \ell ν$ decays. The hadronic mass moments, together with other observables of inclusive $B$ decays, can be used to determine the CKM matrix element $|{V_{cb}}|$ and mass of the $b$-quark $m_b$ in the context of Heavy Quark Expansions of QCD. The Belle~II data recorded at the $Υ(4S)$ resonance in 2019 and 2020 (March-July), corresponding to an integrated luminosity of $34.6\;\mathrm{fb}^{-1}$, is used for this measurement. The decay $Υ(4S) \rightarrow B \overline{B}$ is reconstructed by applying the hadronic tagging algorithm provided by the Full Event Interpretation to fully reconstruct one $B$ meson. The second $B$ meson is reconstructed inclusively by selecting a high-momentum lepton. The $X_c$ system is identified by the remaining reconstructed tracks and clusters in the electromagnetic calorimeter. We report preliminary results for the hadronic mass moments $\langle M_X^n \rangle $ with $n=1,\dots,6$, measured as a function of a lower cut on the lepton momentum in the signal $B$ rest frame.

We consider the effect of massive spin-2 gravitons that occur as Kaluza-Klein excitations of the graviton in a Weak scale Quantum Gravity scenario on the process $\gamma \gamma \to ZZ$, which in the Standard Model can proceed through loop diagrams. For a wide range of parameters, we show that the massive gravitons leave behind signatures that should be verifiable in a TeV scale scattering experiment.

We report measurements related to hadronic $B$ decays to final states that contain charm mesons. The analyses are performed on a $62.8~\mathrm{fb}^{-1}$ data set collected by the Belle II experiment at a center-of-mass energy corresponding to the mass of the $Υ(4S)$ resonance. The measurements reported are for the decay modes $B^-\to D^0 h^-$, $B^{-}\to D^{*0}h^-$, $\bar{B}^{0}\to D^{+} h^{-}$ and $\bar{B}^{0}\to D^{*+} h^{-}$, where $h=π$ or $K$. These modes are either signal or control channels for measurements related to the unitarity triangle angle $γ$ in direct or time-dependent $CP$-violation measurements. The reported observables are the ratios between the $B\to D^{(*)}K$ and $B\to D^{(*)}π$ decay rates, which are found to be in agreement with previous measurements.

The CMS experiment at the LHC selects events with a two-level trigger system, the Level-1 (L1) trigger, and the high-level trigger (HLT). The HLT reduces the rate from 100 to about 1 kHz and has access to the full detector readout and runs a streamlined version of the offline event reconstruction. During LHC Run-2, the peak instantaneous luminosity reached values up to 2.0×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">34</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , posing a challenge to the online event selection. An overview of the HLT system at CMS, the online physics object reconstruction, and the main triggers using those physics objects in 2016-2018 proton collision data-taking period is presented. The performance of a representative set of physics triggers is also discussed.

The reconstruction and identification of tau leptons decaying to hadrons are crucial for new physics signatures and precision measurements with tau leptons in the final state at the LHC. The recently deployed tau identification algorithm using deep neural network (DNN) at the CMS experiment for the discrimination of hadronic tau decays from quark or gluon induced jets, electrons, or muons is an ideal example for the exploitation of modern deep learning neural network techniques in high energy physics. With this algorithm, significant suppression of tau misidentification rates has been achieved for the same identification efficiency compared to previous algorithms at the LHC, leading to considerable performance gains for physics studies with tau leptons. This new multiclass DNN-based tau identification algorithm at CMS and its performance are presented in this article.

The results of the search for the Standard Model (SM) Higgs Boson with the CMS detector in proton-proton collisions at the LHC at 7 TeV center-of-mass energy are reported. A large number of the Higgs Boson decay channels in the mass range from 110 GeV to 600 GeV are considered, and combined upper limits on the production cross section as a function of the Higgs Boson mass are derived. The SM Higgs is excluded at 95% confidence level in the mass range between 127.5 GeV and 600 GeV. In addition, searches for Higgs Bosons in scenarios Beyond the Standard Model (BSM) lead to improved constraints on the Higgs sector of BSM theories such as supersymmetry.

The results on the standard model Higgs boson in lepton decay channels with tau pair and muon pair final states using 25 fb−1 of pp collision data at 7 and 8 TeV centerof-mass energies collected by the CMS detector at the LHC has been summarized. A direct evidence of the Higgs-lepton coupling is established with the tau pair decay mode. Searches for Higgs bosons decaying to leptons in scenarios beyond the standard model such as supersymmetry within the minimal extension of the model has also been reported.

Results for the Standard Model Higgs Boson search are presented in the final states consisting of either two tau leptons or a bottom quark pair, based on proton-proton collision data collected in the years 2011 and 2012 at 7 and 8 TeV respectively with the CMS experiment. Leptonic and hadronic decay channels for the tau lepton are included in the search. Different production mechanisms namely gluon fusion, vector boson fusion and associated production with vector bosons have been studied. The Standard Model Higgs boson search in the b ¯ b decay channel is studied in associated production with W and Z bosons. Interpretations of the data in the Minimal Supersymmetric Standard Model have also be given for both tt and b¯ b decay modes with the Higgs boson utilizing the final state for associated production with a b-jet to enhance the sensitivity of the minimal supersymmetric Higgs coupling to bottom quarks.

La these decrit une etude de l'etat final en paire de leptons tau dans le mode de desintegration semi-leptonique en muons et hadrons en utilisant des donnees proton-proton collisions a une energie de centre de masse de 7 TeV avec le detecteur CMS au CERN Large Hadron Collider. La performance de l'algorithme de reconstruction et d'identification des leptons tau est etudiee en utilisant un echantillon de donnees de collisions proton-proton a $ sqrt $ = 7 TeV, ce qui correspond a une luminosite integree de 36 pb $ ^ {-1} $. Les leptons tau qui se desintegrent en un seul hadron charge, avec ou sans hadrons neutres sont reconstruits a l'aide de la technique dite du flot de particules pour la reconstruction des objets en utilisant un nouvel algorithme adapte aux leptons tau et appele le Hadrons Plus Strips (HPS) qui utilise le trajectographe et le calorimetre electromagnetique de CMS. L'efficacite de l'algorithme de reconstruction est mesuree en utilisant les leptons taus produits lors de la desintegration de bosons Z. Le taux de mauvaise identification de leptons tau se desintegrant de maniere hadronique pour les jets produits en association avec un boson W est egalement determine. La premiere mesure inclusive de production Z $ rightarrow tau tau $ dans les collisions pp au le LHC est presentee dans les etats finals muon+jets en utilisant un echantillon de donnees de 36 pb $ ^ {-1} $. La section efficace mesuree est en bon accord avec les predictions QCD a l'ordre doublement suivant l'ordre dominant (NNLO). Apres avoir identifie le boson Z dans le mode de desintegration di-tau, une recherche inclusive de bosons de Higgs neutres du modele supersymetrique standard minimal (MSSM) dans les collisions pp est realisee a une energie dans le centre de masse de 7 TeV. Les resultats sont bases sur un echantillon de donnees correspondant a une luminosite integree de 36 pb $ ^ {-1} $ et de 4,6 $ fb ^ {-1} $ enregistre par l'experience CMS dans l'annee 2010 et 2011 respectivement. La recherche utilise les desintegrations de bosons de Higgs en paire de leptons tau. Aucun exces n'est observee dans le spectre de masse invariante de paires de leptons tau. Les limites superieures sur le produit de la section efficace de production de boson de Higgs par le rapport de branchement de la desintegration en paire de leptons tau en fonction de la masse du boson de Higgs pseudoscalaire permettent de donner des limites strictes dans l'espace des parametres du MSSM.

After the discovery of the Higgs boson, the ATLAS and CMS experiments have performed combined measurements of the mass of the Higgs boson and also measurements of the production and decay rates, as well as constraints on its couplings to vector bosons and fermions. These combined LHC measurements from the proton-proton collision Run-1 data will be summarized. In addition, the first results from the CMS experiment, on the way to the rediscovery of the Higgs boson in different production and decay modes with the early Run-2 data will also be presented in this paper.

We investigate the phenomenological consequences of the possible existence of the radion at a TeV-scale for γγ scattering in the TeV-range. We find that polarized cross-sections only give possible experimental signatures for the radion.

This letter presents a search for the rare flavor-changing neutral current process $B^{0}\rightarrow K^{\ast 0}\tau^{+}\tau^{-}$ using data taken with the Belle detector at the KEKB asymmetric energy $e^{+}e^{-}$ collider. The analysis is based on the entire $\Upsilon(4S)$ resonance data sample of 711 $\rm fb^{-1}$, corresponding to $772\times 10^{6} B \bar{B}$ pairs. In our search we fully reconstruct the companion $B$ meson produced in the process $e^{+}e^{-}\rightarrow\Upsilon(4S)\rightarrow B\bar{B}$ from its hadronic decay modes, and look for the decay $B^{0}\rightarrow K^{\ast 0}\tau^{+}\tau^{-}$ in the rest of the event. No evidence for a signal is found. We report an upper limit on the branching fraction $\mathcal{B}({B^{0}\rightarrow K^{\ast 0}\tau^{+}\tau^{-}})<2.0\times 10^{-3}$ at 90\% confidence level. This is the first direct limit on $\mathcal{B}({B^{0}\rightarrow K^{\ast 0}\tau^{+}\tau^{-}})$.

Neutrinoless double beta decay is one of the most sensitive approaches in non-accelerator particle physics to take us into a regime of physics beyond the standard model. This article is a brief review of the experiments in search of neutrinoless double beta decay from 76Ge. Following a brief introduction of the process of double beta decay from 76Ge, the results of the very first experiments IGEX and Heidelberg-Moscow which give indications of the existence of possible neutrinoless double beta decay mode has been reviewed. Then ongoing efforts to substantiate the early findings are presented and the Majorana experiment as a future experimental approach which will allow a very detailed study of the neutrinoless decay mode is discussed.

Though the predictions of the standard model (SM) are in excellent agreement with experiments, there are still several theoretical problems associated with the Higgs sector of the SM, where it is widely believed that some new physics will take over at the TeV scale. One beyond the SM theory which resolves these problems is the Little Higgs (LH) model. In this work we have investigated the effects of the LH model on γγ → γγ scattering [1].

Since Run-1 of the LHC, CMS has taken the opportunity to improve further particle reconstruction. A number of improvements were made to the hadronic tau reconstruction and identification algorithms. In particular, the reconstruction of the tau decay products leaving deposits in the electromagnetic calorimeter was improved to better model signal of [Formula: see text] from [Formula: see text] decays. This modification improves energy response and removes the tau footprint from isolation area. In addition to this, improvements were made to discriminators that combine isolation and tau lifetime variables, and the rejection of electrons misidentified as hadronic taus was improved using multivariate techniques. The results of these improvements using 13 TeV data at LHC Run-2 are presented and validation of tau identification using a variety of techniques has been highlighted.

As part of the High Luminosity LHC detector upgrade programme, the CMS experiment is developing a High Granularity Calorimeter (HGCAL) to replace the existing endcap calorimeters. The HGCAL will be realised as a sampling calorimeter, including 36 layers of silicon pads and 14 layers combining both silicon and scintillator detectors interspersed with metal absorber plates. Prototype modules based on 6-inch hexagonal silicon pad sensors with pad areas of 1.0 cm2 have been constructed. Beam tests of different sampling configurations made from these modules have been conducted at the CERN SPS using beams of charged hadrons and electrons with momenta ranging from 20 to 300 GeV/c. The setup was complemented with a CALICE Analog Hadronic Calorimeter (AHCAL) prototype, a scintillator-based sampling calorimeter, mimicking the proposed design of the HGCAL scintillator part. Test beam measurements at CERN in October 2018 are presented, including measurements of pedestal and noise, calibration with single charged particles and energy reconstruction performance of electron and hadron induced showers. Measurements of the timing capabilities of this prototype system are also reported.

As part of its HL-LHC upgrade program, the CMS Collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with $\sim$30,000 hexagonal silicon modules. Prototype modules have been constructed with 6-inch hexagonal silicon sensors with cell areas of 1.1~$cm^2$, and the SKIROC2-CMS readout ASIC. Beam tests of different sampling configurations were conducted with the prototype modules at DESY and CERN in 2017 and 2018. This paper describes the construction and commissioning of the CE calorimeter prototype, the silicon modules used in the construction, their basic performance, and the methods used for their calibration.

Tag-side reconstruction is an important method for reconstructing $B$ meson decays with missing energy. The Belle II tag-side reconstruction algorithm, Full Event Interpretation, relies on a hierarchical reconstruction of $B$ meson decays with multivariate classification employed at each stage of reconstruction. Given the large numbers of classifiers employed and decay chains reconstructed, the performance of the algorithm on data and simulation differs significantly. Here, calibration factors are derived for hadronic tag-side $B$ decays by measuring a signal side decay, $B \rightarrow X\ell ν$, in $34.6$ fb$^{-1}$ of Belle II data. For a very loose selection on the tag-side $B$ multivariate classifier, the calibration factors are $0.65 \pm 0.02$ and $0.83 \pm 0.03$ for tag-side $B^{+}$ and $B^{0}$ mesons, respectively.

Though the predictions of the Standard Model (SM) are in excellent agreement with experiments there are still several theoretical problems associated with the Higgs sector of the SM, where it is widely believed that some ``{\it new physics}'' will take over at the TeV scale. One beyond the SM theory which resolves these problems is the Little Higgs (LH) model. In this work we have investigated the effects of the LH model on $\gggg$ scattering \cite{Choudhury:2006xa}.

The nature of the modification to neutrino lensing from galaxies, as caused by possible modifications to Newtonian gravity at large distances, is studied.

We present systematic measurements of azimuthal anisotropy for strange and multi-strange hadrons ($K^{0}_{s}$, $\Lambda$, $\Xi$, and $\Omega$) and $\phi$-mesons at mid-rapidity ($|y| <$ 1.0) in collisions of U+U nuclei at $\sqrt{s_{NN}} = 193$ GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). Transverse momentum ($p_{\text{T}}$) dependence of flow coefficients ($v_{2}$, $v_{3}$, and $v_{4}$) is presented for minimum bias collisions and three different centrality intervals. The results are obtained using the $\eta$ sub-event plane method. These measurements are compared with the published results from Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Number of Constituent Quark (NCQ) scaling of the measured flow coefficients in U+U collisions is discussed. We also present the ratio of $v_{n}$ scaled by the participant eccentricity ($\varepsilon_{n}\left\lbrace 2 \right\rbrace$) to explore system size dependence and collectivity in U+U collisions. The magnitude of $v_{2}/\varepsilon_{2}$ is found to be smaller in U+U collisions than that in central Au+Au collisions contradicting naive eccentricity scaling. Furthermore, the ratios between various flow harmonics ($v_{3}/v_{2}^{3/2}$, $v_{4}/v_{2}^{4/2}$) are studied as they are sensitive to the properties of the medium and mechanism of hadronization. The measured flow coefficients and the ratios between different flow harmonics are compared with hydrodynamic and transport model calculations.

For the first time we search for the ηc2(1D) in e+e−→γηc2(1D) at s=10.52, 10.58, and 10.867 GeV with data samples of 89.5 fb−1, 711 fb−1, and 121.4 fb−1, respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant ηc2(1D) signal is observed in the mass range between 3.8 and 3.88 GeV/c2. The upper limit at 90% confidence level on the product of the Born cross section for e+e−→γηc2(1D) and branching fraction for ηc2(1D)→γhc(1P) is determined to be σ(e+e−→γηc2(1D))B(ηc2(1D)→γhc(1P))<4.9 fb at s near 10.6 GeV.Received 18 June 2021Accepted 12 July 2021DOI:https://doi.org/10.1103/PhysRevD.104.012012Published 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.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle productionPhysical SystemsQuarkoniaTechniquesLepton collidersParticles & Fields

Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive $J/\psi$ at mid-rapidity in $p$+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV is presented. Such effects are quantified utilizing the nuclear modification factor, $R_{p\mathrm{Au}}$, obtained by taking a ratio of $J/\psi$ yield in $p$+Au collisions to that in $p$+$p$ collisions scaled by the number of binary nucleon-nucleon collisions. The differential $J/\psi$ yield in both $p$+$p$ and $p$+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the $J/\psi$ $R_{p\mathrm{Au}}$ is derived within the transverse momentum ($p_{\mathrm{T}}$) range of 0 to 10 GeV/$c$. A suppression of approximately 30% is observed for $p_{\mathrm{T}}<2$ GeV/$c$, while $J/\psi$ $R_{p\mathrm{Au}}$ becomes compatible with unity for $p_{\mathrm{T}}$ greater than 3 GeV/$c$, indicating the $J/\psi$ yield is minimally affected by the CNM effects at high $p_{\mathrm{T}}$. Comparison to a similar measurement from 0-20% central Au+Au collisions reveals that the observed strong $J/\psi$ suppression above 3 Gev/$c$ is mostly due to the hot medium effects, providing strong evidence for the formation of the quark-gluon plasma in these collisions. Several model calculations show qualitative agreement with the measured $J/\psi$ $R_{p\mathrm{Au}}$, while their agreement with the $J/\psi$ yield in $p$+$p$ and $p$+Au collisions is worse.

We report measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive jet and dijet production in polarized proton-proton collisions at midrapidity and center-of-mass energy $\sqrt{s}$ = 510 GeV, using the high luminosity data sample collected by the STAR experiment in 2013. These measurements complement and improve the precision of previous STAR measurements at the same center-of-mass energy that probe the polarized gluon distribution function at partonic momentum fraction 0.015 $\lesssim x \lesssim$ 0.25. The dijet asymmetries are separated into four jet-pair topologies, which provide further constraints on the $x$ dependence of the polarized gluon distribution function. These measurements are in agreement with previous STAR measurements and with predictions from current next-to-leading order global analyses. They provide more precise data at low dijet invariant mass that will better constraint the shape of the polarized gluon distribution function of the proton.

We report the first observation of the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(1\mathrm{S},2\mathrm{S})\ensuremath{\eta}$ at $\sqrt{s}=10.866\text{ }\text{ }\mathrm{GeV}$, with significance exceeding $10\ensuremath{\sigma}$ for both processes. The measured Born cross sections are $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(2\mathrm{S})\ensuremath{\eta})=2.07\ifmmode\pm\else\textpm\fi{}0.21\ifmmode\pm\else\textpm\fi{}0.19\text{ }\text{ }\mathrm{pb}$, and $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(1\mathrm{S})\ensuremath{\eta})=0.42\ifmmode\pm\else\textpm\fi{}0.08\ifmmode\pm\else\textpm\fi{}0.04\text{ }\text{ }\mathrm{pb}$. We also set the upper limit on the cross section of the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(1\mathrm{S}){\ensuremath{\eta}}^{\ensuremath{'}}$ to be $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(1\mathrm{S}){\ensuremath{\eta}}^{\ensuremath{'}})&lt;0.037\text{ }\text{ }\mathrm{pb}$ at 90% C.L. The results are obtained with the data sample collected with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider in the energy range from 10.63 to 11.02 GeV.