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: 187Citation - Scopus: 313Observation of Higgs Boson Decay To Bottom Quarks(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerThe observation of the standard model (SM) Higgs boson decay to a pair of bottom quarks is presented. The main contribution to this result is from processes in which Higgs bosons are produced in association with a W or Z boson (VH), and are searched for in final states including 0, 1, or 2 charged leptons and two identified bottom quark jets. The results from the measurement of these processes in a data sample recorded by the CMS experiment in 2017, comprising 41.3 fb-1 of proton-proton collisions at s=13 TeV, are described. When combined with previous VH measurements using data collected at s=7, 8, and 13 TeV, an excess of events is observed at mH=125 GeV with a significance of 4.8 standard deviations, where the expectation for the SM Higgs boson is 4.9. The corresponding measured signal strength is 1.01±0.22. The combination of this result with searches by the CMS experiment for H→bb in other production processes yields an observed (expected) significance of 5.6 (5.5) standard deviations and a signal strength of 1.04±0.20.Article Citation - WoS: 38Citation - Scopus: 30Observation of the Chi(b1)(3p) and Chi(b2)(3p) and Measurement of Their Masses(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerThe χb1(3P) and χb2(3P) states are observed through their (3S)γ decays, using an event sample of proton-proton collisions collected by the CMS experiment at the CERN LHC. The data were collected at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 80.0 fb-1. The (3S) mesons are identified through their dimuon decay channel, while the low-energy photons are detected after converting to e+e- pairs in the silicon tracker, leading to a χb(3P) mass resolution of 2.2 MeV. This is the first time that the J=1 and 2 states are well resolved and their masses individually measured: 10513.42±0.41(stat)±0.18(syst) MeV and 10524.02±0.57(stat)±0.18(syst) MeV; they are determined with respect to the world-average value of the ~(3S) mass, which has an uncertainty of 0.5 MeV. The mass splitting is measured to be 10.60±0.64(stat)±0.17(syst) MeV.Article Citation - WoS: 92Citation - Scopus: 211Search for Heavy Neutral Leptons in Events With Three Charged Leptons in Proton-Proton Collisions at ?s = 13 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerA search for a heavy neutral lepton N of Majorana nature decaying into a W boson and a charged lepton is performed using the CMS detector at the LHC. The targeted signature consists of three prompt charged leptons in any flavor combination of electrons and muons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV, with an integrated luminosity of 35.9 fb-1. The search is performed in the N mass range between 1 GeV and 1.2 TeV. The data are found to be consistent with the expected standard model background. Upper limits are set on the values of |VeN|2 and |VμN|2, where V N is the matrix element describing the mixing of N with the standard model neutrino of flavor. These are the first direct limits for N masses above 500 GeV and the first limits obtained at a hadron collider for N masses below 40 GeV.Article Citation - WoS: 70Citation - Scopus: 76Observation of Correlated Azimuthal Anisotropy Fourier Harmonics in Pp and P+pb Collisions at the Lhc(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerThe azimuthal anisotropy Fourier coefficients (vn) in 8.16 TeV p+Pb data are extracted via long-range two-particle correlations as a function of the event multiplicity and compared to corresponding results in pp and PbPb collisions. Using a four-particle cumulant technique, vn correlations are measured for the first time in pp and p+Pb collisions. The v2 and v4 coefficients are found to be positively correlated in all collision systems. For high-multiplicity p+Pb collisions, an anticorrelation of v2 and v3 is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in p+Pb and PbPb collisions in the measured multiplicity range.Article Citation - WoS: 121Citation - Scopus: 185Observation of Electroweak Production of Same-Sign W Boson Pairs in the Two Jet and Two Same-Sign Lepton Final State in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2018) Karapınar, GülerThe first observation of electroweak production of same-sign W boson pairs in proton-proton collisions is reported. The data sample corresponds to an integrated luminosity of 35.9 fb-1 collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. Events are selected by requiring exactly two leptons (electrons or muons) of the same charge, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass. The observed significance of the signal is 5.5 standard deviations, where a significance of 5.7 standard deviations is expected based on the standard model. The ratio of measured event yields to that expected from the standard model at leading order is 0.90±0.22. A cross section measurement in a fiducial region is reported. Bounds are given on the structure of quartic vector boson interactions in the framework of dimension-8 effective field theory operators and on the production of doubly charged Higgs bosons.Article Citation - WoS: 41Citation - Scopus: 71Search for Charged Higgs Bosons Produced Via Vector Boson Fusion and Decaying Into a Pair of W and Z Bosons Using Pp Collisions at ?s =13 Tev(American Physical Society, 2017) CMS Collaboration; Karapınar, GülerA search for charged Higgs bosons produced via vector boson fusion and decaying into W and Z bosons using proton-proton collisions at s=13 TeV is presented. The data sample corresponds to an integrated luminosity of 15.2 fb-1 collected with the CMS detector in 2015 and 2016. The event selection requires three leptons (electrons or muons), two jets with large pseudorapidity separation and high dijet mass, and missing transverse momentum. The observation agrees with the standard model prediction. Limits on the vector boson fusion production cross section times branching fraction for new charged physical states are reported as a function of mass from 200 to 2000 GeV and interpreted in the context of Higgs triplet models.Article Citation - WoS: 32Citation - Scopus: 67Study of Jet Quenching With Z+jet Correlations in Pb-Pb and Pp Collisions at S Nn=5.02 Tev(American Physical Society, 2017) CMS Collaboration; Karapınar, GülerThe production of jets in association with Z bosons, reconstructed via the μ+μ- and e+e- decay channels, is studied in pp and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%-30% centrality range. The back-to-back azimuthal alignment was studied in both pp and Pb-Pb collisions for Z bosons with transverse momentum pTZ>60 GeV/c and a recoiling jet with pTjet>30 GeV/c. The pT imbalance xjZ=pTjet/pTZ, as well as the average number of jet partners per Z, RjZ, was studied in intervals of pTZ. The RjZ is found to be smaller in Pb-Pb than in pp collisions, which suggests that in Pb-Pb collisions a larger fraction of partons associated with the Z bosons fall below the 30 GeV/c pTjet threshold because they lose energy.Article Citation - WoS: 45Citation - Scopus: 48Study of B Meson Production in P+pb Collisions at ?snn = 5.02 Tev Using Exclusive Hadronic Decays(American Physical Society, 2016) CMS Collaboration; Karapınar, GülerThe production cross sections of the B+, B0, and Bs0 mesons, and of their charge conjugates, are measured via exclusive hadronic decays in p+Pb collisions at the center-of-mass energy √SNN = 5.02 TeV with the CMS detector at the CERN LHC. The data set used for this analysis corresponds to an integrated luminosity of 34.6 nb-1. The production cross sections are measured in the transverse momentum range between 10 and 60 GeV/c. No significant modification is observed compared to proton-proton perturbative QCD calculations scaled by the number of incoherent nucleon-nucleon collisions. These results provide a baseline for the study of in-medium b quark energy loss in Pb+Pb collisions. © 2016 CERN.Article Citation - WoS: 53Citation - Scopus: 55Measurement of Prompt ? (2s) To J /? Yield Ratios in Pb-Pb and P - P Collisions at Snn =2.76 Tev(American Physical Society, 2014) CMS Collaboration; Karapınar, GülerThe ratio between the prompt ψ(2S) and J/ψ yields, reconstructed via their decays into μ+μ-, is measured in Pb-Pb and p-p collisions at sNN=2.76 TeV. The analysis is based on Pb-Pb and p-p data samples collected by CMS at the Large Hadron Collider, corresponding to integrated luminosities of 150 μb-1 and 5.4 pb-1, respectively. The double ratio of measured yields (Nψ(2S)/NJ/ψ)Pb-Pb/(Nψ(2S)/NJ/ψ)p-p is computed in three Pb-Pb collision centrality bins and two kinematic ranges: one at midrapidity, |y|<1.6, covering the transverse momentum range 6.5<pT<30 GeV/c, and the other at forward rapidity, 1.6<|y|<2.4, extending to lower pT values, 3<pT<30 GeV/c. The centrality-integrated double ratio changes from 0.45±0.13(stat)±0.07(syst) in the first range to 1.67±0.34(stat)±0.27(syst) in the second. This difference is most pronounced in the most central collisions. © 2014 CERN. © 2014 CERN, for the The CMS Collaboration. Published by the American Physical Society under the terms of the »http://creativecommons.org/licenses/by/3.0/» Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Article Citation - WoS: 215Citation - Scopus: 239Observation of Sequential Suppression in Pbpb Collisions(American Physical Society, 2012) CMS Collaboration; Karapınar, GülerThe suppression of the individual Υ(nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150μb -1 and 230nb-1, respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76TeV. The Υ(nS) yields are measured from the dimuon invariant mass spectra. The suppression of the Υ(nS) yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, RAA, is measured as a function of the collision centrality. Integrated over centrality, the RAA values are 0.56±0.08(stat)±0.07(syst), 0.12±0.04(stat)±0.02(syst), and lower than 0.10 (at 95% confidence level), for the Υ(1S), Υ(2S), and Υ(3S) states, respectively. The results demonstrate the sequential suppression of the Υ(nS) states in PbPb collisions at LHC energies. © 2012 CERN.
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