WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 47Searches for light- and heavy-flavour three-jet resonances in Pp collisions at root S=8 Tev(Elsevier Ltd., 2014) Karapınar, Güler; CMS CollaborationA search for three-jet hadronic resonance production in pp collisions at a centre-of-mass energy of 8 TeV has been conducted by the CMS Collaboration at the LHC with a data sample corresponding to an integrated luminosity of 19.4 fb(-1). The search method is model independent, and events are selected that have high jet multiplicity and large values of jet transverse momenta. The signal models explored assume R-parity-violating supersymmetric gluino pair production and have final states with either only light-flavour jets or both light- and heavy-flavour jets. No significant deviation is found between the selected events and the expected standard model multijet and t (t) over bar background. For a gluino decaying into light-flavour jets, a lower limit of 650 GeV on the gluino mass is set at a 95% confidence level, and for a gluino decaying into one heavy- and two light-flavour jets, gluino masses between 200 and 835 GeV are, for the first time, likewise excluded. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).Article Citation - WoS: 185Modification of jet shapes in Pbpb collisions at root S(nn)=2.76 Tev(Elsevier Ltd., 2014) Karapınar, Güler; CMS CollaborationThe first measurement of jet shapes, defined as the fractional transverse momentum radial distribution, for inclusive jets produced in heavy-ion collisions is presented. Data samples of PbPb and pp collisions, corresponding to integrated luminosities of 150 mu b(-1) and 5.3 pb(-1) respectively, were collected at a nucleon-nucleon centre-of-mass energy of root s(NN) = 2.76 TeV with the CMS detector at the LHC. The jets are reconstructed with the anti-k(T) algorithm with a distance parameter R = 0.3, and the jet shapes are measured for charged particles with transverse momentum P-T > 1 GeV/c. The jet shapes measured in PbPb collisions in different collision centralities are compared to reference distributions based on the pp data. A centrality-dependent modification of the jet shapes is observed in the more central PbPb collisions, indicating a redistribution of the energy inside the jet cone. This measurement provides information about the parton shower mechanism in the hot and dense medium produced in heavy-ion collisions. (C) 2014 The Authors. Published by Elsevier B.V.Article Citation - WoS: 13Search for baryon number violation in top-quark decays(Elsevier Ltd., 2014) Karapınar, Güler; CMS CollaborationA search for baryon number violation (BNV) in top-quark decays is performed using pp collisions produced by the LHC at root s = 8 TeV. The top-quark decay considered in this search results in one light lepton (muon or electron), two jets, but no neutrino in the final state. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 19.5 fb(-1). The event selection is optimized for top quarks produced in pairs, with one undergoing the BNV decay and the other the standard model hadronic decay to three jets. No significant excess of events over the expected yield from standard model processes is observed. The upper limits at 95% confidence level on the branching fraction of the BNV top-quark decay are calculated to be 0.0016 and 0.0017 for the muon and the electron channels, respectively. Assuming lepton universality, an upper limit of 0.0015 results from the combination of the two channels. These limits are the first that have been obtained on a BNV process involving the top quark. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY licenseArticle Citation - WoS: 57Citation - Scopus: 62Measurement of the W Boson Helicity Fractions in the Decays of Top Quark Pairs To Lepton Plus Jets Final States Produced in Pp Collisions at Root S=8 Tev(Elsevier Ltd., 2016) Karapınar, Güler; CMS CollaborationThe W boson helicity fractions from top quark decays in t (t) over bar events are measured using data from proton-proton collisions at a centre-of-mass energy of 8 TeV. The data were collected in 2012 with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb(-1). Events are reconstructed with either one muon or one electron, along with four jets in the final state, with two of the jets being identified as originating from b quarks. The measured helicity fractions from both channels are combined, yielding F-0 = 0.681 +/- 0.012 (stat) +/- 0.023 (syst), F-L = 0.323 +/- 0.008 (stat) +/- 0.014 (syst), and F-R = -0.004 +/- 0.005 (stat) +/- 0.014 (syst) for the longitudinal, left-, and right-handed components of the helicity, respectively. These measurements of the W boson helicity fractions are the most accurate to date and they agree with the predictions from the standard model. (C) 2016 The Author. Published by Elsevier B.V.Article Citation - WoS: 40Citation - Scopus: 50Search for Heavy Gauge W ' Bosons in Events With an Energetic Lepton and Large Missing Transverse Momentum at Root S=13tev(Elsevier Ltd., 2017) Karapınar, Güler; CMS CollaborationA search is presented for W' bosons in events with an electron or muon and large missing transverse momentum, using proton-proton collision data at root s = 13 TeV collected with the CMS detector in 2015 and corresponding to an integrated luminosity of 2.3 fb(-1). No evidence of an excess of events relative to the standard model expectations is observed. For a W' boson described by the sequential standard model, upper limits at 95% confidence level are set on the product of the production cross section and branching fraction and lower limits are established on the new boson mass. Masses below 4.1 TeV are excluded combining electron and muon decay channels, significantly improving upon the results obtained with the 8 TeV data. Exclusion limits at 95% confidence level on the product of the W' production cross section and branching fraction are also derived in combination with the 8 TeV data. Finally, exclusion limits are set for the production of generic W' bosons decaying into this final state using a model-independent approach. (C) 2017 The Author. Published by Elsevier B.V.Article Citation - WoS: 22Citation - Scopus: 26Search for Black Holes and Other New Phenomena in High-Multiplicity Final States in Proton-Proton Collisions at Root S=13 Tev(Elsevier Ltd., 2017) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Karapınar, Güler; CMS CollaborationA search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 fb(-1). The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data. (c) 2017 The Author(s). Published by Elsevier B.V.Article Citation - WoS: 35Citation - Scopus: 42Search for the Pair Production of Third-Generation Squarks With Two-Body Decays To a Bottom or Charm Quark and a Neutralino in Proton-Proton Collisions at Root S=13 Tev(Elsevier Ltd., 2018) Karapınar, Güler; CMS CollaborationResults are presented from a search for the pair production of third-generation squarks in proton-proton collision events with two-body decays to bottom or charm quarks and a neutralino, which produces a significant imbalance in the transverse momentum. The search is performed using a sample of proton-proton collision data at root s = 13 TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9fb(-1). No statistically significant excess of events is observed beyond the expected contribution from standard model processes. Exclusion limits are set in the context of simplified models of bottom or top squark pair production. Models with bottom squark masses up to 1220 GeV are excluded at 95% confidence level for light neutralinos, and models with top squark masses of 510 GeV are excluded assuming that the mass splitting between the top squark and the neutralino is small. (C) 2018 The Author. Published by Elsevier B.V.Article Citation - WoS: 40Citation - Scopus: 46Measurement of the Associated Production of a Single Top Quark and a Z Boson in Pp Collisions At, Root S=13 Tev(Elsevier Ltd., 2018) Karapınar, Güler; CMS CollaborationA measurement is presented of the associated production of a single top quark and a Z boson. The study uses data from proton-proton collisions at, root s = 13 TeV recorded by the CMS experiment, corresponding to an integrated luminosity of 35.9 fb(-1). Using final states with three leptons (electrons or muons), the tZq production cross section is measured to be sigma (pp -> tZq -> Wbl(+)l(-)q) = 123(-31)(+33)(stat)(-23)(+29)(syst) fb, where l stands for electrons, muons, or tau leptons, with observed and expected significances of 3.7 and 3.1 standard deviations, respectively. C) 2018 The Author. Published by Elsevier B.V.Article Citation - WoS: 24Citation - Scopus: 27Search for Supersymmetry With Higgs Boson To Diphoton Decays Using the Razor Variables at Root S=13 Tev(Elsevier Ltd., 2018) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Karapınar, Güler; CMS CollaborationAn inclusive search for anomalous Higgs boson production in the diphoton decay channel and in association with at least one jet is presented, using LHC proton-proton collision data collected by the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 35.9 fb(-1). The razor variables M-R and R-2, as well as the momentum and mass resolution of the diphoton system, are used to categorize events into different search regions. The search result is interpreted in the context of strong and electroweak production of supersymmetric particles. We exclude bottom squark pair-production with masses below 450 GeV for bottom squarks decaying to a bottom quark, a Higgs boson, and the lightest supersymmetric particle (LSP) for LSP masses below 250 GeV. For wino-like chargino-neutralino production, we exclude charginos with mass below 170 GeV for LSP masses below 25 GeV. In the GMSB scenario, we exclude charginos with mass below 205 GeV for neutralinos decaying to a Higgs boson and a goldstino LSP with 100% branching fraction. C) 2018 The Author(s). Published by Elsevier B.V.Article Citation - WoS: 74Citation - Scopus: 80Search for Pair Production of Vector-Like Quarks in the Bw(b)over-Barw Channel From Proton-Proton Collisions at Root S=13tev(Elsevier Ltd., 2018) Karapınar, Güler; CMS CollaborationA search is presented for the production of vector-like quark pairs, T (T) over bar or Y (Y) over bar, with electric charge of 2/3(T) or -4/3(Y), in proton-proton collisions at root s= 13 TeV. The data were collected by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.8 fb(-1). The T and Y quarks are assumed to decay exclusively to a W boson and a b quark. The search is based on events with a single isolated electron or muon, large missing transverse momentum, and at least four jets with large transverse momenta. In the search, a kinematic reconstruction of the final state observables is performed, which would permit a signal to be detected as a narrow mass peak (approximate to 7% resolution). The observed number of events is consistent with the standard model prediction. Assuming strong pair production of the vector-like quarks and a 100% branching fraction to bW, a lower limit of 1295 GeV at 95% confidence level is set on the T and Y quark masses. (c) 2018 The Author(s). Published by Elsevier B.V.