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: 28Citation - Scopus: 46Constraining Gluon Distributions in Nuclei Using Dijets in Proton-Proton and Proton-Lead Collisions at ?s Nn = 5.02 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyThe pseudorapidity distributions of dijets as functions of their average transverse momentum (pTave) are measured in proton-lead (pPb) and proton-proton (pp) collisions. The data samples were collected by the CMS experiment at the CERN LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. A significant modification of the pPb spectra with respect to the pp spectra is observed in all pTave intervals investigated. The ratios of the pPb and pp distributions are compared to next-to-leading order perturbative quantum chromodynamics calculations with unbound nucleon and nuclear parton distribution functions (PDFs). These results give the first evidence that the gluon PDF at large Bjorken x in lead ions is strongly suppressed with respect to the PDF in unbound nucleons.Article Citation - WoS: 69Citation - Scopus: 123Measurement of the Splitting Function in Pp and Pb-Pb Collisions at ?s N N = 5.02 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyData from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Article Citation - WoS: 37Citation - Scopus: 62Suppression of Excited States Relative To the Ground State in Pb-Pb Collisions at S Nn = 5.02 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyThe relative yields of mesons produced in pp and Pb-Pb collisions at sNN=5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, (2S) and (3S), to the ground state, (1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [(nS)/(1S)]Pb-Pb/[(nS)/(1S)]pp, are measured to be 0.308±0.055(stat)±0.019(syst) for the (2S) and less than 0.26 at 95% confidence level for the (3S). No significant (3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as transverse momentum and rapidity. No significant dependencies are observed.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, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyThe 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: 179Citation - Scopus: 117Search for New Physics in the Multijet and Missing Transverse Momentum Final State in Proton-Proton Collisions at ?s=7tev(American Physical Society, 2012) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA search for physics beyond the standard model is performed in events with at least three jets and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of √s=7TeV. No significant excess of events above the expected backgrounds is observed in 4.98fb -1 of data collected with the CMS detector at the Large Hadron Collider. The results are presented in the context of the constrained minimal supersymmetric extension of the standard model and more generically for simplified models. For the simplified models of gluino-gluino and squark-squark production, gluino masses below 1.0 TeV and squark masses below 0.76 TeV are excluded in case the lightest supersymmetric particle mass is below 200 GeV. These results significantly extend previous searches. © 2012 CERN. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License.Article Citation - WoS: 86Citation - Scopus: 109Study of Z Boson Production in Pbpb Collisions at ?s Nn=2.76tev(American Physical Society, 2011) Karapınar, Güler; Karapınar, Güler; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA 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: 243Citation - Scopus: 216Indications of Suppression of Excited? States in Pb-Pb Collisions at Snn2.76 Tev(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş Ali; Karapınar, Güler; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA comparison of the relative yields of Υ resonances in the μ+μ- decay channel in Pb-Pb and pp collisions at a center-of-mass energy per nucleon pair of 2.76TeV is performed with data collected with the CMS detector at the LHC. Using muons of transverse momentum above 4GeV/c and pseudorapidity below 2.4, the double ratio of the Υ(2S) and Υ(3S) excited states to the Υ(1S) ground state in Pb-Pb and pp collisions, [Υ(2S+3S)/Υ(1S)]Pb-Pb/[Υ(2S+3S)/Υ(1S) ]pp, is found to be 0.31-0.15+0.19(stat)±0.03(syst). The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%. © 2011 American Physical Society.