Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 165Citation - Scopus: 122Search for a Higgs Boson in the Mass Range From 145 To 1000 Gev Decaying To a Pair of W or Z Bosons(Springer Verlag, 2015) CMS Collaboration; Karapınar, GülerA search for a heavy Higgs boson in the H → WW and H → ZZ decay channels is reported. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 fb−1 at √ s = 7 TeV and up to 19.7fb−1 at √ s = 8 TeV, recorded by the CMS experiment at the CERN LHC. Several final states of the H → WW and H → ZZ decays are analyzed. The combined upper limit at the 95% confidence level on the product of the cross section and branching fraction exclude a Higgs boson with standard model-like couplings and decays in the range 145 < mH < 1000 GeV. We also interpret the results in the context of an electroweak singlet extension of the standard model.[Figure not available: see fulltext.] © 2015, The Author(s).Article Citation - WoS: 91Citation - Scopus: 81Identification Techniques for Highly Boosted W Bosons That Decay Into Hadrons(Springer Verlag, 2014) CMS Collaboration; Karapınar, GülerIn searches for new physics in the energy regime of the LHC, it is becoming increasingly important to distinguish single-jet objects that originate from the merging of the decay products of W bosons produced with high transverse momenta from jets initiated by single partons. Algorithms are defined to identify such W jets for different signals of interest, using techniques that are also applicable to other decays of bosons to hadrons that result in a single jet, such as those from highly boosted Z and Higgs bosons. The efficiency for tagging W jets is measured in data collected with the CMS detector at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb−1. The performance of W tagging in data is compared with predictions from several Monte Carlo simulators.Article Citation - WoS: 52Citation - Scopus: 40Measurement of the Production Cross Sections for a Z Boson and One or More B Jets in Pp Collisions at ?s = 7 Tev(Springer Verlag, 2014) CMS Collaboration; Karapınar, GülerThe production of a Z boson, decaying into two leptons and produced in association with one or more b jets, is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV. The data were recorded in 2011 with the CMS detector and correspond to an integrated luminosity of 5 fb-1. The Z(ℓℓ) + b-jets cross sections (where ℓℓ = μμ or ee) are measured separately for a Z boson produced with exactly one b jet and with at least two b jets. In addition, a cross section ratio is extracted for a Z boson produced with at least one b jet, relative to a Z boson produced with at least one jet. The measured cross sections are compared to various theoretical predictions, and the data favour the predictions in the five-flavour scheme, where b quarks are assumed massless. The kinematic properties of the reconstructed particles are compared with the predictions from the MadGraph event generator using the pythia parton shower simulation.Article Citation - WoS: 63Citation - Scopus: 51Search for Top-Squark Pairs Decaying Into Higgs or Z Bosons in Pp Collisions at S=8 Tev(Elsevier Ltd., 2014) CMS Collaboration; Karapınar, GülerA search for supersymmetry through the direct pair production of top squarks, with Higgs (H) or Z bosons in the decay chain, is performed using a data sample of proton-proton collisions at s=8 TeV collected in 2012 with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 19.5 fb-1. The search is performed using a selection of events containing leptons and bottom-quark jets. No evidence for a significant excess of events over the standard model background prediction is observed. The results are interpreted in the context of simplified supersymmetric models with pair production of a heavier top-squark mass eigenstate t~2 decaying to a lighter top-squark mass eigenstate t~1 via either t~2→Ht~1 or t~2→Zt~1, followed in both cases by t~1→tχ~10, where χ~10 is an undetected, stable, lightest supersymmetric particle. The interpretation is performed in the region where the mass difference between the t~1 and χ~10 states is approximately equal to the top-quark mass (mt~1-mχ~10≃mt), which is not probed by searches for direct t~1 squark pair production. The analysis excludes top squarks with masses mt~2<575 GeV and mt~1<400 GeV at a 95% confidence level. © 2014 The Authors.Article Citation - WoS: 17Citation - Scopus: 17Search for Exotic Resonances Decaying Into Wz/Zz in Pp Collisions at ?s=7 Tev(Springer Verlag, 2013) CMS Collaboration; Karapınar, GülerA search for new exotic particles decaying to the VZ final state is performed, where V is either a W or a Z boson decaying into two overlapping jets and the Z decays into a pair of electrons, muons or neutrinos. The analysis uses a data sample of pp collisions corresponding to an integrated luminosity of 5 fb-1 collected by the CMS experiment at the LHC at √s=7 TeV in 2011. No significant excess is observed in the mass distribution of the VZ candidates compared with the background expectation from standard model processes. Model-dependent upper limits at the 95% confidence level are set on the product of the cross section times the branching fraction of hypothetical particles decaying to the VZ final state as a function of mass. Sequential standard model W′ bosons with masses between 700 and 940 GeV are excluded. In the Randall-Sundrum model for graviton resonances with a coupling parameter of 0.05, masses between 750 and 880 GeV are also excluded. © 2013 CERN for the benefit of the CMS collaboration.Article Citation - WoS: 56Citation - Scopus: 92Study of Exclusive Two-Photon Production of W+w- in Pp Collisions at ?s=7 Tev and Constraints on Anomalous Quartic Gauge Couplings(Springer Verlag, 2013) CMS Collaboration; Karapınar, GülerA search for exclusive or quasi-exclusive W+W- production by photon-photon interactions, pp → p(*)W +W-p(*), at √s=7 TeV is reported using data collected by the CMS detector with an integrated luminosity of 5.05 fb-1. Events are selected by requiring a μ ±e∓ vertex with no additional associated charged tracks and dilepton transverse momentum p T(μ ±e∓) > 30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2 ± 0.4 signal events with 0.84 ± 0.15 background. The tail of the dilepton p T distribution is studied for deviations from the standard model. No events are observed with p T > 100 GeV. Model-independent upper limits are computed and compared to predictions involving anomalous quartic gauge couplings. The limits on the parameters α0,C W/λ2 with a dipole form factor and an energy cutoff Λcutoff = 500 GeV are of the order of 10-4. © 2013 CERN for the benefit of the CMS collaboration.Article Citation - WoS: 24Citation - Scopus: 30Search for a W' or Techni-? Decaying Into Wz in Pp Collisions at ?s=7tev(American Physical Society, 2012) CMS Collaboration; Karapınar, GülerA search is performed in pp collisions at √s=7TeV for exotic particles decaying via WZ to final states with electrons and muons. The data sample corresponds to an integrated luminosity of approximately 5fb -1. No significant excess is observed in the data above the expected standard model background. Upper bounds at 95% confidence level are set on the production cross section of the W ′ boson described by the sequential standard model and on the W ′ WZ coupling. W ′ bosons with masses below 1143 GeV are excluded. Limits are also set in the context of low-scale technicolor models, under a range of assumptions concerning the model parameters. © 2012 CERN.Article Citation - WoS: 87Citation - Scopus: 115Measurement of the B+ Production Cross Section in Pp Collisions at ?s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliMeasurements of the total and differential cross sections dσ/dpTB and dσ/dyB for B+ mesons produced in pp collisions at √s=7TeV are presented. The data correspond to an integrated luminosity of 5.8pb-1 collected by the CMS experiment operating at the LHC. The exclusive decay B+→J/ψK+, with J/ψ→μ+μ-, is used to detect B+ mesons and to measure the production cross section as a function of pTB and yB. The total cross section for pTB>5GeV and |yB|<2.4 is measured to be 28.1±2.4±2.0±3.1μb, where the first uncertainty is statistical, the second is systematic, and the last is from the luminosity measurement. © 2011 American Physical Society.Article Citation - WoS: 86Citation - Scopus: 109Study of Z Boson Production in Pbpb Collisions at ?s Nn=2.76tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for Z bosons in the μ+μ- decay channel has been performed in PbPb collisions at √sNN=2.76TeV with the CMS detector at the LHC, in a 7.2μb-1 data sample. The number of opposite-sign muon pairs observed in the 60-120GeV/c2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of [33.8±5.5(stat)±4.4(syst)]×10-8, in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions. © 2011 American Physical Society.Article Citation - WoS: 75Citation - Scopus: 80Search for Neutral Minimal Supersymmetric Standard Model Higgs Bosons Decaying To Tau Pairs in Pp Collisions at ?s=7tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş AliA search for neutral minimal supersymmetric standard model (MSSM) Higgs bosons in pp collisions at the LHC at a center-of-mass energy of 7 TeV is presented. The results are based on a data sample corresponding to an integrated luminosity of 36pb-1 recorded by the CMS experiment. The search uses decays of the Higgs bosons to tau pairs. No excess is observed in the tau-pair invariant-mass spectrum. The resulting upper limits on the Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, yield stringent new bounds in the MSSM parameter space. © 2011 American Physical Society.