Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
8 results
Search Results
Article Citation - WoS: 60Citation - Scopus: 67Measurement of Prompt and Nonprompt J / Ψ Production in P P and P Pb Collisions at √snn=5.02tev(Springer Nature, 2017) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Abbaneo, D.; 01. Izmir Institute of TechnologyThis paper reports the measurement of J / ψ meson production in proton–proton (p p) and proton–lead (p Pb) collisions at a center-of-mass energy per nucleon pair of 5.02TeV by the CMS experiment at the LHC. The data samples used in the analysis correspond to integrated luminosities of 28pb-1 and 35nb-1 for p p and p Pb collisions, respectively. Prompt and nonprompt J / ψ mesons, the latter produced in the decay of B hadrons, are measured in their dimuon decay channels. Differential cross sections are measured in the transverse momentum range of 2<pT<30GeV/c, and center-of-mass rapidity ranges of | yCM| < 2.4 (p p) and - 2.87 < yCM< 1.93 (p Pb). The nuclear modification factor, Rp Pb, is measured as a function of both pT and yCM. Small modifications to the J / ψ cross sections are observed in p Pb relative to p p collisions. The ratio of J / ψ production cross sections in p -going and Pb-going directions, RFB, studied as functions of pT and yCM, shows a significant decrease for increasing transverse energy deposited at large pseudorapidities. These results, which cover a wide kinematic range, provide new insight on the role of cold nuclear matter effects on prompt and nonprompt J / ψ production. © 2017, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 26Citation - Scopus: 32Searches for Pair Production of Third-Generation Squarks in √s=13tev Pp Collisions(Springer Nature, 2017) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Trevisani, N.; 01. Izmir Institute of TechnologySearches are presented for direct production of top or bottom squark pairs in proton–proton collisions at the CERN LHC. Two searches, based on complementary techniques, are performed in all-jet final states that are characterized by a significant imbalance in transverse momentum. An additional search requires the presence of a charged lepton isolated from other activity in the event. The data were collected in 2015 at a centre-of-mass energy of 13TeV with the CMS detector and correspond to an integrated luminosity of 2.3fb-1. No statistically significant excess of events is found beyond the expected contribution from standard model processes. Exclusion limits are set in the context of simplified models of top or bottom squark pair production. Models with top and bottom squark masses up to 830 and 890GeV, respectively, are probed for light neutralinos. For models with top squark masses of 675GeV, neutralino masses up to 260GeV are excluded at 95% confidence level. © 2017, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 25Citation - Scopus: 32Measurement of the Top Quark Mass Using Single Top Quark Events in Proton-Proton Collisions at √s=8 Tev(Springer Nature, 2017) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Auffray, E.; 01. Izmir Institute of TechnologyA measurement of the top quark mass is reported in events containing a single top quark produced via the electroweak t channel. The analysis is performed using data from proton-proton collisions collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb- 1. Top quark candidates are reconstructed from their decay to a W boson and a b quark, with the W boson decaying leptonically to a muon and a neutrino. The final state signature and kinematic properties of single top quark events in the t channel are used to enhance the purity of the sample, suppressing the contribution from top quark pair production. A fit to the invariant mass distribution of reconstructed top quark candidates yields a value of the top quark mass of 172.95±0.77(stat)-0.93+0.97(syst)GeV. This result is in agreement with the current world average, and represents the first measurement of the top quark mass in event topologies not dominated by top quark pair production, therefore contributing to future averages with partially uncorrelated systematic uncertainties and a largely uncorrelated statistical uncertainty. © 2017, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 67Citation - Scopus: 74Measurement of Double-Differential Cross Sections for Top Quark Pair Production in Pp Collisions at √s=8tev and Impact on Parton Distribution Functions(Springer Nature, 2017) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Ball, A.H.; 01. Izmir Institute of TechnologyNormalized double-differential cross sections for top quark pair (t t ¯) production are measured in pp collisions at a centre-of-mass energy of 8TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7fb-1. The measurement is performed in the dilepton e ±μ∓ final state. The t t ¯ cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and t t ¯ system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured t t ¯ cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution. © 2017, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 14Citation - Scopus: 30Search for the Production of W±w±w Events at S =13 Tev(American Physical Society, 2019) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Azhgirey, I.; 01. Izmir Institute of TechnologyA search for the production of events containing three W bosons predicted by the standard model is reported. The search is based on a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the CMS experiment at the CERN LHC and corresponding to a total integrated luminosity of 35.9 fb-1. The search is performed in final states with three leptons (electrons or muons), or with two same-charge leptons plus two jets. The observed (expected) significance of the signal for W±W±W production is 0.60 (1.78) standard deviations, and the ratio of the measured signal yield to that expected from the standard model is 0.34-0.34+0.62. Limits are placed on three anomalous quartic gauge couplings and on the production of massive axionlike particles. © 2019 CERN.Article Citation - WoS: 57Citation - Scopus: 90Search for Vectorlike Leptons in Multilepton Final States in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2019) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Bitioukov, S.; 01. Izmir Institute of TechnologyA search for vectorlike leptons in multilepton final states is presented. The data sample corresponds to an integrated luminosity of 77.4 fb-1 of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2016 and 2017. Events are categorized by the multiplicity of electrons, muons, and hadronically decaying τ leptons. The missing transverse momentum and the scalar sum of the lepton transverse momenta are used to distinguish the signal from background. The observed results are consistent with the expectations from the standard model hypothesis. The existence of a vectorlike lepton doublet, coupling to the third-generation standard model leptons in the mass range of 120-790 GeV, is excluded at 95% confidence level. These are the most stringent limits yet on the production of a vectorlike lepton doublet, coupling to the third-generation standard model leptons. © 2019 CERN, for the CMS Collaboration.Article Citation - WoS: 12Citation - Scopus: 20Measurement of the Top Quark Yukawa Coupling From T T Kinematic Distributions in the Lepton+jets Final State in Proton-Proton Collisions at S =13 Tev Measurement of the Top Quark Yukawa Coupling From ... Sirunyan Et Al.(American Physical Society, 2019) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Bitioukov, S.; 01. Izmir Institute of TechnologyResults are presented for an extraction of the top quark Yukawa coupling from top quark-antiquark (tt) kinematic distributions in the lepton plus jets final state in proton-proton collisions, based on data collected by the CMS experiment at the LHC at s=13 TeV, corresponding to an integrated luminosity of 35.8 fb-1. Corrections from weak boson exchange, including Higgs bosons, between the top quarks can produce large distortions of differential distributions near the energy threshold of tt production. Therefore, precise measurements of these distributions are sensitive to the Yukawa coupling. Top quark events are reconstructed with at least three jets in the final state, and a novel technique is introduced to reconstruct the tt system for events with one missing jet. This technique enhances the experimental sensitivity in the low invariant mass region, Mtt. The data yields in Mtt, the rapidity difference |yt-yt|, and the number of reconstructed jets are compared with distributions representing different Yukawa couplings. These comparisons are used to measure the ratio of the top quark Yukawa coupling to its standard model predicted value to be 1.07-0.43+0.34 with an upper limit of 1.67 at the 95% confidence level. © 2019 CERN.Article Citation - WoS: 28Citation - Scopus: 46Search for Long-Lived Particles Using Delayed Photons in Proton-Proton Collisions at S =13 Tev(American Physical Society, 2019) Sirunyan, A.M.; Karapınar, Güler; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Babaev, A.; 01. Izmir Institute of TechnologyA search for long-lived particles decaying to photons and weakly interacting particles, using proton-proton collision data at s=13 TeV collected by the CMS experiment in 2016-2017 is presented. The data set corresponds to an integrated luminosity of 77.4 fb-1. Results are interpreted in the context of supersymmetry with gauge-mediated supersymmetry breaking, where the neutralino is long-lived and decays to a photon and a gravitino. Limits are presented as a function of the neutralino proper decay length and mass. For neutralino proper decay lengths of 0.1, 1, 10, and 100 m, masses up to 320, 525, 360, and 215 GeV are excluded at 95% confidence level, respectively. We extend the previous best limits in the neutralino proper decay length by up to one order of magnitude, and in the neutralino mass by up to 100 GeV. © 2019 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/" Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.