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: 26Citation - Scopus: 54Search for Heavy Stable Charged Particles in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe result of a search at the LHC for heavy stable charged particles produced in pp collisions at root s = 7TeV is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb(-1). Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398 GeV/c(2), using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c(2) is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.Article Citation - WoS: 153Citation - Scopus: 137Strange Particle Production in Pp Collisions at Root S=0.9 and 7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7TeV. The K-S(0), A, and Xi(-) particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum, p(T). The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The p(T) distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.Article Citation - WoS: 18Citation - Scopus: 29Search for Large Extra Dimensions in the Diphoton Final State at the Large Hadron Collider(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA search for large extra spatial dimensions via virtual-graviton exchange in the diphoton channel has been carried out with the CMS detector at the LHC. No excess of events above the standard model expectations is found using a data sample collected in proton-proton collisions at root s = 7TeV and corresponding to an integrated luminosity of 36 pb(-1). New lower limits on the effective Planck scale in the range of 1.6-2.3TeV at the 95% confidence level are set, providing the most restrictive bounds to date on models with more than two large extra dimensions.Article Citation - WoS: 14Citation - Scopus: 32Search for Physics Beyond the Standard Model in Opposite-Sign Dilepton Events in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA search is presented for physics beyond the standard model (SM) in final states with opposite-sign isolated lepton pairs accompanied by hadronic jets and missing transverse energy. The search is performed using LHC data recorded with the CMS detector, corresponding to an integrated luminosity of 34 pb(-1). No evidence for an event yield beyond SM expectations is found. An upper limit on the non-SM contribution to the signal region is deduced from the results. This limit is interpreted in the context of the constrained minimal supersymmetric model. Additional information is provided to allow testing the exclusion of specific models of physics beyond the SM.Article Citation - WoS: 14Citation - Scopus: 50Search for Supersymmetry in Events With a Lepton, a Photon, and Large Missing Transverse Energy in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA search is performed for an excess of events, over the standard model expectations, with a photon, a lepton, and large missing transverse energy in pp collisions root s = 7TeV. Such events are expected in many new physics models, in particular a theory that is broken via a gauge-mediated mechanism, when the lightest and neutral gauginos are mass degenerate. The data sample used in this search to an integrated luminosity of 35 pb(-1) collected with the CMS detector at the No evidence of such an excess above the standard model backgrounds, dominated by production, is found. The results are presented as 95% confidence level upper limits on the cross section for a benchmark gauge-mediated scenario, and are then converted into exclusion limits on the squark, gluino, and wino masses.Article Citation - WoS: 30Citation - Scopus: 37Search for Supersymmetry in Events With B Jets and Missing Transverse Momentum at the Lhc(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA search for supersymmetry is presented using a sample of events with b jets and missing transverse momentum. The search uses a data sample of proton-proton collisions at a centre-of-mass energy of 7TeV, corresponding to an integrated luminosity of 35 pb(-1), collected with the CMS detector. A total of 0.33(-0.33)(+0.43) (stat.) +/- 0.13 (syst.) events is predicted, using control samples in the data, to arise from standard model processes, and one event is observed in the data. Upper limits are set at the 95% confidence level on the cross sections of benchmark supersymmetric models.Article Citation - WoS: 25Citation - Scopus: 87Measurement of the T(t)over-Bar Production Cross Section and the Top Quark Mass in the Dilepton Channel in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe t (t) over bar production cross section and top quark mass are measured in proton-proton collisions at root s = 7 TeV in a data sample corresponding to an integrated luminosity of 36 pb(-1) collected by the CMS experiment. The measurements are performed in events with two leptons (electrons or muons) in the final state. Results of the cross section measurement in events with and without b-quark identification are obtained and combined. The measured value is sigma(tt) - 168 +/- 18 (stat:) +/- 14 (syst:) +/- 7 (lumi:) pb, consistent with predictions from the standard model. The top quark mass m(top) is reconstructed with two different methods, a full kinematic analysis and a matrix weighting technique. The combination yields a measurement of m(top) = 175.5 +/- 4.6 (stat:) +/- 4: 6 (syst:) GeV/c(2).Article Citation - WoS: 39Citation - Scopus: 45Search for Same-Sign Top-Quark Pair Production at Root S=7 Tev and Limits on Flavour Changing Neutral Currents in the Top Sector(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliAn inclusive search for same-sign top-quark pair production in pp collisions at root s = 7 TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 pb(-1). This analysis is motivated by recent studies of p (p) over bar -> t (t) over bar reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor Changing Neutral Currents (FCNC) in the top sector induced by t -channel exchange of a massive neutral vector boson (Z'). Models with such a Z' also predict enhancement of same-sign top-pair production in pp or pp collisions. Limits are set as a function of the Z' mass and its couplings to u and t quarks. These limits disfavour the FCNC interpretation of the Tevatron results.Article Citation - WoS: 102Citation - Scopus: 120Dependence on Pseudorapidity and on Centrality of Charged Hadron Production in Pbpb Collisions at Root S(nn)=2.76 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA measurement is presented of the charged hadron multiplicity in hadronic PbPb collisions, as a function of pseudorapidity and centrality, at a collision energy of 2.76 TeV per nucleon pair. The data sample is collected using the CMS detector and a minimum-bias trigger, with the CMS solenoid off. The number of charged hadrons is measured both by counting the number of reconstructed particle hits and by forming hit doublets of pairs of layers in the pixel detector. The two methods give consistent results. The charged hadron multiplicity density, dN(ch)/d eta vertical bar(eta=0), for head-on collisions is found to be 1612 +/- 55, where the uncertainty is dominated by systematic effects. Comparisons of these results to previous measurements and to various models are also presented.Article Citation - WoS: 42Citation - Scopus: 38Measurement of the Inclusive Z Cross Section Via Decays To Tau Pairs in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe first measurement of inclusive Z > tau(+) tau(-) production in pp collisions at the LHC is presented, in the final states mu+hadrons, e+hadrons, e-mu, and mu+mu. The data sample corresponds to an integrated luminosity of 36 pb(-1) collected with the CMS detector. The measured cross section is sigma (pp -> ZX) x B (Z -> tau(+)tau(-)) = 1.00 +/- 0.05 (stat.)+/- 0.08 (syst.) +/- 0.04 (lumi.) nb, which is in good agreement with the next-to-next-to-leading order QCD prediction and improves on previous measurements in the Z -> e(+)e(-) and mu(+)mu(-) channels. The reconstruction efficiency for hadronic T decays is determined with a precision of 7%.