Browsing by Author "Bergauer, T."

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Citation - WoS: 5
Addendum: Measurement and Qcd Analysis of Double-Differential Inclusive Jet Cross Sections in Proton-Proton Collisions at Root S=13 Tev
(Springer, 2022) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Del Valle, A. Escalante; Gürpınar Güler, Emine; Güler, Yalçın
The QCD analysis at NNLO is repeated by using the NNLO interpolation grids for the double-differential inclusive jet cross section [1], which were released after the journal publication of the original analysis. The NNLOJET calculation used to derive these grids is based on the leading-colour and leading-flavour-number approximation and does not include the most recent subleading colour contributions. However, these contributions were reported in ref. [2] to be very small in inclusive jet production, in particular for a jet size of R = 0.7. The grids also contain an estimate of the numerical integration uncertainty of around 1% or less. To account for point-to-point fluctuations, this uncertainty, after consultation with the authors of NNLOJET, has been increased by a factor of two; however, its impact in the fit is negligible. A comparison of the measurement with predictions using various PDFs is shown in figure 1. Although the PDF parametrisation remains identical, higher precision in PDF and QCD parameters is expected by using NNLO grids consistently in the QCD analysis. These new results supersede those obtained by using the k-factor technique.
Citation - WoS: 37
Citation - Scopus: 46
Analysis of the Cp Structure of the Yukawa Coupling Between the Higgs Boson and Tau Leptons in Proton-Proton Collisions at Root S=13 Tev
(Springer, 2022) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Güler, Yalçın; The CMS Collaboration
The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and tau leptons is presented. The measurement is based on data collected in proton-proton collisions at root s = 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb(-1). The analysis uses the angular correlation between the decay planes of tau leptons produced in Higgs boson decays. The effective mixing angle between CP-even and CP-odd tau Yukawa couplings is found to be -1 +/- 19 degrees, compared to an expected value of 0 +/- 21 degrees at the 68.3% confidence level. The data disfavour the pure CP-odd scenario at 3.0 standard deviations. The results are compatible with predictions for the standard model Higgs boson.
Citation - WoS: 1
Angular Analysis of the B0 → K*(892)0μ+μ- Decay in Proton-Proton Collisions at √s=13 TeV
(Elsevier, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Benato, L.; Bergauer, T.; Kumar, A.
A full set of optimized observables is measured in an angular analysis of the decay B-0 -> K*(892)(0)mu(+)mu(-) using a sample of proton-proton collisions at root s = 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 140 fb(-1). The analysis is performed in six bins of the squared invariant mass of the dimuon system, q(2), over the range 1.1 < q(2) < 16 GeV2. The results are among the most precise experimental measurements of the angular observables for this decay and are compared to a variety of predictions based on the standard model. Some of these predictions exhibit tension with the measurements.
Citation - WoS: 5
Citation - Scopus: 5
Azimuthal Anisotropy of Dijet Events in Pbpb Collisions at √snn=5.02 Tev
(SPRINGER, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Gürpınar Güler, Emine; Güler, Yalçın
The path-length dependent parton energy loss within the dense partonic medium created in lead-lead collisions at a nucleon-nucleon center-of-mass energy of root s(NN) = 5.02TeV is studied by determining the azimuthal anisotropies for dijets with high transverse momentum. The data were collected by the CMS experiment in 2018 and correspond to an integrated luminosity of 1.69 nb(-1). For events containing back-to-back jets, correlations in relative azimuthal angle and pseudorapidity (eta) between jets and hadrons, and between two hadrons, are constructed. The anisotropies are expressed as the Fourier expansion coefficients v(n), n = 2-4 of these azimuthal distributions. The dijet v(n) values are extracted from long-range (1.5 < vertical bar Delta eta vertical bar < 2.5) components of these correlations, which suppresses the background contributions from jet fragmentation processes. Positive dijet v(2) values are observed which increase from central to more peripheral events, while the v(3) and v(4) values are consistent with zero within experimental uncertainties.
Citation - WoS: 2
Citation - Scopus: 3
Azimuthal Correlations in Z +jets Events in Proton–proton Collisions at √s=13tev
(Institute for Ionics, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Tok, U.G.; Gürpınar Güler, Emine; Güler, Yalçın
The production of Z bosons associated with jets is measured in pp collisions at s=13TeV with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3 fb-1 . The multiplicity of jets with transverse momentum pT>30GeV is measured for different regions of the Z boson’s pT(Z) , from lower than 10 GeV to higher than 100 GeV . The azimuthal correlation Δϕ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of pT(Z) . The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low pT(Z) regions. © 2023, The Author(s).
Citation - WoS: 1
Citation - Scopus: 4
Bottom Quark Energy Loss and Hadronization With B+ and Bs0 Nuclear Modification Factors Using pp and Pbpb Collisions at Snn = 5.02 TeV
(Springer Science and Business Media Deutschland GmbH, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Makarenko, V.
The production cross sections of Bs0 and B+ mesons are reported in proton-proton (pp) collisions recorded by the CMS experiment at the CERN LHC with a center-of-mass energy of 5.02 TeV. The data sample corresponds to an integrated luminosity of 302 pb−1. The cross sections are based on measurements of the Bs0→ J/ψ(μ+μ−)ϕ(1020)(K+K−) and B+→ J/ψ(μ+μ−)K+ decay channels. Results are presented in the transverse momentum (pT) range 7–50 GeV/c and the rapidity interval |y| < 2.4 for the B mesons. The measured pT-differential cross sections of B+ and Bs0 in pp collisions are well described by fixed-order plus next-to-leading logarithm perturbative quantum chromodynamics calculations. Using previous PbPb collision measurements at the same nucleon-nucleon center-of-mass energy, the nuclear modification factors, RAA, of the B mesons are determined. For pT> 10 GeV/c, both mesons are found to be suppressed in PbPb collisions (with RAA values significantly below unity), with less suppression observed for the Bs0 mesons. In this pT range, the RAA values for the B+ mesons are consistent with those for inclusive charged hadrons and D0 mesons. Below 10 GeV/c, both B+ and Bs0 are found to be less suppressed than either inclusive charged hadrons or D0 mesons, with the Bs0RAA value consistent with unity. The RAA values found for the B+ and Bs0 are compared to theoretical calculations, providing constraints on the mechanism of bottom quark energy loss and hadronization in the quark-gluon plasma, the hot and dense matter created in ultrarelativistic heavy ion collisions. © The Author(s) 2025.
Citation - WoS: 11
Citation - Scopus: 12
Cms Pythia 8 Colour Reconnection Tunes Based on Underlying-Event Data
(Institute for Ionics, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Akgun, B.; Gürpınar Güler, Emine; Güler, Yalçın
New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia 8 event generator, are obtained based on the default CMS pythia 8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies s=7 and 13 TeV , and by the CDF experiment at 1.96 TeV are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13 TeV including measurements of the underlying-event, strange-particle multiplicities, jet substructure observables, jet shapes, and colour flow in top quark pair (t t ¯) events. The new tunes are also used to estimate the uncertainty related to colour reconnection modelling in the top quark mass measurement using the decay products of t t ¯ events in the semileptonic channel at 13 TeV . © 2023, The Author(s).
Citation - WoS: 25
Citation - Scopus: 18
Combination of Measurements of the Top Quark Mass From Data Collected by the Atlas and Cms Experiments at √=7 and 8 Tev
(American Physical Society, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Gürpınar Güler, Emine; Güler, Yalçın
A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The datasets used correspond to an integrated luminosity of up to 5 and Formula Presented of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak Formula Presented channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is Formula Presented, with a total uncertainty of 0.33 GeV. © 2024 CERN, for the CMS and ATLASs Collaboration.
Citation - WoS: 13
Citation - Scopus: 21
Combined Search for Electroweak Production of Winos, Binos, Higgsinos, and Sleptons in Proton-Proton Collisions at Formula Presented
(American Physical Society, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Gürpınar Güler, Emine; Güler, Yalçın
A combination of the results of several searches for the electroweak production of the supersymmetric partners of standard model bosons, and of charged leptons, is presented. All searches use proton-proton collision data at Formula Presented recorded with the CMS detector at the LHC in 2016-2018. The analyzed data correspond to an integrated luminosity of up to Formula Presented. The results are interpreted in terms of simplified models of supersymmetry. Two new interpretations are added with this combination: a model spectrum with the bino as the lightest supersymmetric particle together with mass-degenerate Higgsinos decaying to the bino and a standard model boson, and the compressed-spectrum region of a previously studied model of slepton pair production. Improved analysis techniques are employed to optimize sensitivity for the compressed spectra in the wino and slepton pair production models. The results are consistent with expectations from the standard model. The combination provides a more comprehensive coverage of the model parameter space than the individual searches, extending the exclusion by up to 125 GeV, and also targets some of the intermediate gaps in the mass coverage. © 2024 CERN, for the CMS Collaboration.
Citation - WoS: 34
Citation - Scopus: 49
Combined Searches for the Production of Supersymmetric Top Quark Partners in Proton-Proton Collisions at Root S=13 Tev
(SPRINGER, 2021) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Vetens, W.; Gürpınar Güler, Emine; Güler, Yalçın; The CMS Collaboration
A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV.
Citation - WoS: 7
Citation - Scopus: 5
Constraints on Anomalous Higgs Boson Couplings From Its Production and Decay Using the Ww Channel in Proton-Proton Collisions at √s=13 Tev
(Springer, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Zhokin, A.
A study of the anomalous couplings of the Higgs boson to vector bosons, including CP-violation effects, has been conducted using its production and decay in the WW channel. This analysis is performed on proton-proton collision data collected with the CMS detector at the CERN LHC during 2016-2018 at a center-of-mass energy of 13 TeV, and corresponds to an integrated luminosity of 138 fb(-1). The different-flavor dilepton (e mu) final state is analyzed, with dedicated categories targeting gluon fusion, electroweak vector boson fusion, and associated production with a W or Z boson. Kinematic information from associated jets is combined using matrix element techniques to increase the sensitivity to anomalous effects at the production vertex. A simultaneous measurement of four Higgs boson couplings to electroweak vector bosons is performed in the framework of a standard model effective field theory. All measurements are consistent with the expectations for the standard model Higgs boson and constraints are set on the fractional contribution of the anomalous couplings to the Higgs boson production cross section.
Citation - WoS: 15
Citation - Scopus: 24
Constraints on Anomalous Higgs Boson Couplings To Vector Bosons and Fermions From the Production of Higgs Bosons Using the Tt Final State
(Amer Physical Soc, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Gürpınar Güler, Emine; Güler, Yalçın
A study of anomalous couplings of the Higgs boson to vector bosons and fermions is presented. The data were recorded by the CMS experiment at a center-of-mass energy of pp collisions at the LHC of 13 TeV and correspond to an integrated luminosity of 138 fb-1. The study uses Higgs boson candidates produced mainly in gluon fusion or electroweak vector boson fusion at the LHC that subsequently decay to a pair of z leptons. Matrix-element and machine-learning techniques were employed in a search for anomalous interactions. The results are combined with those from the four-lepton and two-photon decay channels to yield the most stringent constraints on anomalous Higgs boson couplings to date. The pure CP-odd scenario of the Higgs boson coupling to gluons is excluded at 2.4 standard deviations. The results are consistent with the standard model predictions.
Citation - WoS: 43
Citation - Scopus: 56
Constraints on Anomalous Higgs Boson Couplings To Vector Bosons and Fermions in Its Production and Decay Using the Four-Lepton Final State
(AMER PHYSICAL SOC, 2021) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Vetens, W.; Gürpınar Güler, Emine; Güler, Yalçın; The CMS Collaboration
Studies of CP violation and anomalous couplings of the Higgs boson to vector bosons and fermions are presented. The data were acquired by the CMS experiment at the LHC and correspond to an integrated luminosity of 137 fb(-1) at a proton-proton collision energy of 13 TeV. The kinematic effects in the Higgs boson's four-lepton decay H -> 4l and its production in association with two jets, a vector boson, or top quarks are analyzed, using a full detector simulation and matrix element techniques to identify the production mechanisms and to increase sensitivity to the tensor structure of the Higgs boson interactions. A simultaneous measurement is performed of up to five Higgs boson couplings to electroweak vector bosons (HVV), two couplings to gluons (Hgg), and two couplings to top quarks (Htt). The CP measurement in the Htt interaction is combined with the recent measurement in the H -> gamma gamma channel. The results are presented in the framework of anomalous couplings and are also interpreted in the framework of effective field theory, including the first study of CP properties of the Htt and effective Hgg couplings from a simultaneous analysis of the gluon fusion and top-associated processes. The results are consistent with the standard model of particle physics.
Citation - WoS: 7
Constraints on the Higgs Boson Self-Coupling From the Combination of Svingle and Double Higgs Boson Production in Proton-Proton Collisions at √s=13 Tev
(Elsevier, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Lee, J.
The Higgs boson (H) trilinear self-coupling, lambda(3), is constrained via its measured properties and limits on the HH pair production using the proton-proton collision data collected by the CMS experiment at root s = 13 TeV. The combination of event categories enriched in single-H and HH events is used to measure k(lambda), defined as the value of lambda(3) normalized to its standard model prediction, while simultaneously constraining the Higgs boson couplings to fermions and vector bosons. Values of k(lambda) outside the interval -1.2 < k(lambda) < 7.5 are excluded at 2 sigma confidence level, which is compatible with the expected range of -2.0< k(lambda) < 7.7 under the assumption that all other Higgs boson couplings are equal to their standard model predicted values. Relaxing the assumption on the Higgs couplings to fermions and vector bosons the observed (expected) k(lambda) interval is constrained to be within -1.4 < k(lambda) < 7.8 (-2.3 < k(lambda) < 7.8) at 2 sigma confidence level.
Citation - WoS: 3
Citation - Scopus: 6
Differential Cross Section Measurements for the Production of Top Quark Pairs and of Additional Jets Using Dilepton Events From Pp Collisions at S = 13 Tev
(Springer Science and Business Media Deutschland GmbH, 2025) Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Trapote, A.
Differential cross sections for top quark pair (tt¯) production are measured in proton-proton collisions at a center-of-mass energy of 13 TeV using a sample of events containing two oppositely charged leptons. The data were recorded with the CMS detector at the CERN Large Hadron Collider and correspond to an integrated luminosity of 138 fb−1. The differential cross sections are measured as functions of kinematic observables of the tt¯ system, the top quark and antiquark and their decay products, as well as of the number of additional jets in the event. The results are presented as functions of up to three variables and are corrected to the parton and particle levels. When compared to standard model predictions based on quantum chromodynamics at different levels of accuracy, it is found that the calculations do not always describe the observed data. The deviations are found to be largest for the multi-differential cross sections. © The Author(s) 2025.
Elliptic Anisotropy Measurement of the F0(980) Hadron in Proton-Lead Collisions and Evidence for Its Quark-Antiquark Composition
(Nature Portfolio, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Zhokin, A.
Despite the f(0)(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark (q (q) over bar) meson, a tetraquark (q (q) over barq (q) over bar) exotic state, a kaon-antikaon (K (K) over bar) molecule, or a quark-antiquark-gluon (q (q) over barg) hybrid. This paper reports strong evidence that the f(0)(980) state is an ordinary q (q) over bar meson, inferred from the scaling of elliptic anisotropies (v(2)) with the number of constituent quarks (n(q)), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f(0)(980) state is reconstructed via its dominant decay channel f(0)(980) -> pi(+)pi(-), in proton-lead collisions recorded by the CMS experiment at the LHC, and its v(2) is measured as a function of transverse momentum (p(T)). It is found that the n(q) = 2 (q (q) over bar state) hypothesis is favored over n(q) = 4 (q (q) over barq (q) over bar or K (K) over bar states) by 7.7, 6.3, or 3.1 standard deviations in the p(T) < 10, 8, or 6 GeV/c ranges, respectively, and over n(q) = 3 (q<(q)over bar>g hybrid state) by 3.5 standard deviations in the p(T) < 8GeV/c range. This result represents the first determination of the quark content of the f(0)(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates.
Citation - WoS: 1
Citation - Scopus: 2
Energy-Scaling Behavior of Intrinsic Transverse-Momentum Parameters in Drell-Yan Simulation
(Amer Physical Soc, 2025) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Makarenko, V.
An analysis is presented based on models of the intrinsic transverse momentum (intrinsic k(T)) of partons in nucleons by studying the dilepton transverse momentum in Drell-Yan events. Using parameter tuning in event generators and existing data from fixed-target experiments and from hadron colliders, our investigation spans 3 orders of magnitude in center-of-mass energy and 2 orders of magnitude in dilepton invariant mass. The results show an energy-scaling behavior of the intrinsic k(T) parameters, independent of the dilepton invariant mass at a given center-of-mass energy.
Citation - WoS: 10
Evidence for Four-Top Quark Production in Proton-Proton Collisions at √s=13 Tev
(Elsevier, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Gürpınar Güler, Emine; Güler, Yalçın
The production of four top quarks (tt over bar tt over bar ) is studied with LHC proton-proton collision data samples collected by the CMS experiment at a center-of-mass energy of 13 TeV, and corresponding to integrated luminosities of up to 138 fb-1. Events that have no leptons (all-hadronic), one lepton, or two oppositesign leptons (where lepton refers only to prompt electrons or prompt muons) are considered. This is the first tt over bar tt over bar measurement that includes the all-hadronic final state. The observed significance of the tt over bar tt over bar signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for tt over bar tt over bar production, with a measured cross section of 36+12 signal significance is 4.0 standard deviations (3.2 expected). The combination returns an observed cross section of 17 +/- 4 (stat) +/- 3 (syst) fb, which is consistent with the standard model prediction. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.
Citation - WoS: 13
Evidence for Ww/Wz Vector Boson Scattering in the Decay Channel L Nu Qq Produced in Association With Two Jets in Proton-Proton Collisions at Root S=13tev
(Elsevier, 2022) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Del Valle, A. Escalante; Gürpınar Güler, Emine; Güler, Yalçın
Evidence is reported for electroweak (EW) vector boson scattering in the decay channel l nu qq of two weak vector bosons WV(V = Wor Z), produced in association with two parton jets. The search uses a data set of proton-proton collisions at 13TeVcollected with the CMS detector during 2016-2018 with an integrated luminosity of 138fb(-1). Events are selected requiring one lepton (electron or muon), moderate missing transverse momentum, two jets with a large pseudorapidity separation and a large dijet invariant mass, and a signature consistent with the hadronic decay of a W/Zboson. The cross section is computed in a fiducial phase space defined at parton level requiring all parton transverse momenta p(T)> 10 GeVand at least one pair of outgoing partons with invariant mass mqq> 100 GeV. The measured and expected EW WVproduction cross sections are 1.90(-0.46)(+0.5)3 pb and 2.23(-0.11)(+0.08)(scale) +/- 0.05(PDF) pb, respectively, where PDF is the parton distribution function. The observed EW signal strength is mu EW= 0.85 +/- 0.12 (stat)(-0.17)(+0.19)(syst), corresponding to a signal significance of 4.4 standard deviations with 5.1 expected, and it is measured keeping the quantum chromodynamics (QCD) associated diboson production fixed to the standard model prediction. This is the first evidence of vector boson scattering in the l nu qq decay channel at LHC. The simultaneous measurement of the EW and QCD associated diboson production agrees with the standard model prediction. (C) 2022 The Author(s). Published by Elsevier B.V.
Citation - WoS: 9
Citation - Scopus: 12
Extracting the Speed of Sound in Quark-Gluon Plasma With Ultrarelativistic Lead-Lead Collisions at the Lhc
(Institute of Physics, 2024) Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Gürpınar Güler, Emine; Güler, Yalçın
Ultrarelativistic nuclear collisions create a strongly interacting state of hot and dense quark-gluon matter that exhibits a remarkable collective flow behavior with minimal viscous dissipation. To gain deeper insights into its intrinsic nature and fundamental degrees of freedom, we determine the speed of sound in an extended volume of quark-gluon plasma using lead-lead (PbPb) collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 0.607 nb−1. The measurement is performed by studying the multiplicity dependence of the average transverse momentum of charged particles emitted in head-on PbPb collisions. Our findings reveal that the speed of sound in this matter is nearly half the speed of light, with a squared value of 0.241 ±0.002(stat) ±0.016(syst) in natural units. The effective medium temperature, estimated using the mean transverse momentum, is 219 ±8(syst)MeV. The measured squared speed of sound at this temperature aligns precisely with predictions from lattice quantum chromodynamic (QCD) calculations. This result provides a stringent constraint on the equation of state of the created medium and direct evidence for a deconfined QCD phase being attained in relativistic nuclear collisions. © 2024 CERN, for the benefit of the CMS Collaboration.