PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Citation - WoS: 20Citation - Scopus: 31Search for Flavor-Changing Neutral Current Interactions of the Top Quark and Higgs Boson in Final States With Two Photons in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2022) Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Bunichev, V.Proton-proton interactions resulting in final states with two photons are studied in a search for the signature of flavor-changing neutral current interactions of top quarks (t) and Higgs bosons (H). The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb-1. No significant excess above the background prediction is observed. Upper limits on the branching fractions (B) of the top quark decaying to a Higgs boson and an up (u) or charm (c) quark are derived through a binned fit to the diphoton invariant mass spectrum. The observed (expected) 95% confidence level upper limits are found to be 0.019% (0.031%) for B(t→Hu) and 0.073% (0.051%) for B(t→Hc). These are the strictest upper limits yet determined. © 2022 CERN.Article Citation - WoS: 5Citation - Scopus: 9Search for Resonances Decaying To Three W Bosons in Proton-Proton Collisions at Root S=13 Tev(American Physical Society, 2022) Karapınar, Güler; CMS CollaborationA search for resonances decaying into a W boson and a radion, where the radion decays into two W bosons, is presented. The data analyzed correspond to an integrated luminosity of 138 fb???1 recorded in ffiffiproton-proton collisions with the CMS detector at p s 1/4 13 TeV. One isolated charged lepton is required, together with missing transverse momentum and one or two massive large-radius jets, containing the decay products of either two or one W bosons, respectively. No excess over the background estimation is observed. The results are combined with those from a complementary channel with an all-hadronic final state, described in an accompanying paper. Limits are set on parameters of an extended warped extradimensional model. These searches are the first of their kind at the LHC.Article Citation - WoS: 25Citation - Scopus: 32Using Z Boson Events To Study Parton-Medium Interactions in Pb-Pb Collisions(American Physical Society, 2022) Karapınar, GülerThe spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson arc reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7 nb(-1) and 320 pb(-1), respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum p(T) > 30 GeV/c are analyzed. The Z boson constrains the initial energy and direction of the associated parton. In heavy ion events, azimuthal angular distributions of charged hadrons with respect to the direction of a Z boson are sensitive to modifications of the in-medium parton shower and medium response. compared to reference data from pp interactions, the results for central Pb-Pb collisions indicate a modification of the angular correlations. The measurements of the fragmentation functions and p(T) spectra of charged particles in Z boson events, which are sensitive to medium modifications of the parton shower longitudinal structure, are also reported. Significant modifications in central Pb-Pb events compared to the pp reference data are also found for these observables.Article Citation - WoS: 22Citation - Scopus: 25Observation of the Bc+ Meson in Pb-Pb and Pp Collisions at Snn =5.02 Tev and Measurement of Its Nuclear Modification Factor(American Physical Society, 2022) Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Boos, E.The Bc+ meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the Bc+ meson in lead-lead (Pb-Pb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of sNN=5.02 TeV, via the Bc+→(J/ψ→μ+μ-)μ+νμ decay. The Bc+ nuclear modification factor, derived from the Pb-Pb-to-pp ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the Pb-Pb collision centrality. The Bc+ meson is shown to be less suppressed than quarkonia and most of the open heavy-flavor mesons, suggesting that effects of the hot and dense nuclear matter created in heavy ion collisions contribute to its production. This measurement sets forth a promising new probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma. © 2022 CERN.Article Citation - WoS: 15Citation - Scopus: 21Measurements of the Electroweak Diboson Production Cross Sections in Proton-Proton Collisions at Root S=5.02 Tev Using Leptonic Decays(American Physical Society, 2021) Karapınar, Güler; CMS CollaborationThe first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb(-1). Events with two, three, or four charged light leptons (electrons or muons) in the final state are analyzed. The WW, WZ, and ZZ total cross sections are measured as sigma(WW) = 37:0(-5.2)(+5.5) (stat)(-2.6)(+2.7) (syst) pb, sigma(WZ) = 6.4(-2.1)(+2.5) (stat)(-0.3)(+0.5)(syst) pb, and sigma(ZZ) = 5.3(-2.1)(+2.5)(stat)(-0.4)(+0.5) (syst) pb. All measurements are in good agreement with theoretical calculations at combined next-to-next-to-leading order quantum chromodynamics and next-to-leading order electroweak accuracy.Article Citation - WoS: 32Citation - Scopus: 42Search for Long-Lived Particles Decaying in the Cms End Cap Muon Detectors in Proton-Proton Collisions at Root S=13 Tev(American Physical Society, 2021) Karapınar, Güler; CMS CollaborationA search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb(-1) of proton-proton collisions at root s = 13 TeV, recorded at the LHC in 2016-2018. A novel technique is employed to reconstruct decays of LLPs in the end cap muon detectors. The search is sensitive to a broad range of LLP decay modes and to masses as low as a few GeV. No excess of events above the SM background is observed. The most stringent limits to date on the branching fraction of the Higgs boson to LLPs subsequently decaying to quarks and tau(+)tau(-) are found for proper decay lengths greater than 6, 20, and 40 m, for LLP masses of 7, 15, and 40 GeV, respectively.Article Citation - WoS: 91Citation - Scopus: 133Measurements of T T ¯ H Production and the Cp Structure of the Yukawa Interaction Between the Higgs Boson and Top Quark in the Diphoton Decay Channel(American Physical Society, 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Dragicevic, M.; Skovpen, Y.The first observation of the tt¯H process in a single Higgs boson decay channel with the full reconstruction of the final state (H→γγ) is presented, with a significance of 6.6 standard deviations (σ). The CP structure of Higgs boson couplings to fermions is measured, resulting in an exclusion of the pure CP-odd structure of the top Yukawa coupling at 3.2σ. The measurements are based on a sample of proton-proton collisions at a center-of-mass energy s=13 TeV collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb-1. The cross section times branching fraction of the tt¯H process is measured to be σtt¯HBγγ=1.56-0.32+0.34 fb, which is compatible with the standard model prediction of 1.13-0.11+0.08 fb. The fractional contribution of the CP-odd component is measured to be fCPHtt=0.00±0.33. © 2020 CERN.Article Citation - WoS: 15Citation - Scopus: 16Studies of Charm Quark Diffusion Inside Jets Using Pb-Pb and Pp Collisions at Snn =5.02 Tev(American Physical Society, 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Devetak, D.The first study of charm quark diffusion with respect to the jet axis in heavy ion collisions is presented. The measurement is performed using jets with pTjet>60 GeV/c and D0 mesons with pTD>4 GeV/c in lead-lead (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of sNN=5.02 TeV, recorded by the CMS detector at the LHC. The radial distribution of D0 mesons with respect to the jet axis is sensitive to the production mechanisms of the meson, as well as to the energy loss and diffusion processes undergone by its parent parton inside the strongly interacting medium produced in Pb-Pb collisions. When compared to Monte Carlo event generators, the radial distribution in pp collisions is found to be well described by pythia, while the slope of the distribution predicted by sherpa is steeper than that of the data. In Pb-Pb collisions, compared to the pp results, the D0 meson distribution for 4<pTD<20 GeV/c hints at a larger distance on average with respect to the jet axis, reflecting a diffusion of charm quarks in the medium created in heavy ion collisions. At higher pTD, the Pb-Pb and pp radial distributions are found to be similar. © 2020 CERN.Article Citation - WoS: 33Citation - Scopus: 52Observation of the Production of Three Massive Gauge Bosons at S =13 Tev(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Dremin,I.The first observation is reported of the combined production of three massive gauge bosons (VVV with V=W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis is based on a data sample recorded by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 137 fb-1. The searches for individual WWW, WWZ, WZZ, and ZZZ production are performed in final states with three, four, five, and six leptons (electrons or muons), or with two same-sign leptons plus one or two jets. The observed (expected) significance of the combined VVV production signal is 5.7 (5.9) standard deviations and the corresponding measured cross section relative to the standard model prediction is 1.02-0.23+0.26. The significances of the individual WWW and WWZ production are 3.3 and 3.4 standard deviations, respectively. Measured production cross sections for the individual triboson processes are also reported. © 2020 CERN.Article Citation - WoS: 12Citation - Scopus: 32Observation of the Bs0 →x (3872)φ Decay(American Physical Society, 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Andreev,V.Using a data sample of proton-proton collisions at s=13 TeV, corresponding to an integrated luminosity of 140 fb-1 collected by the CMS experiment in 2016-2018, the Bs0→X(3872)φ decay is observed. Decays into J/ψ+π- and K+K- are used to reconstruct, respectively, the X(3872) and φ. The ratio of the product of branching fractions B[Bs0→X(3872)φ]B[X(3872)→J/ψ+π-] to the product B[Bs0→(2S)φ]B[ψ(2S)→J/ψ+π-] is measured to be [2.21±0.29(stat)±0.17(syst)]%. The ratio B[Bs0→X(3872)φ]/B[B0→X(3872)K0] is found to be consistent with one, while the ratio B[Bs0→X(3872)φ]/B[B+→X(3872)K+] is two times smaller. This suggests a difference in the production dynamics of the X(3872) in B0 and Bs0 meson decays compared to B+. The reported observation may shed new light on the nature of the X(3872) particle. © 2020 CERN.