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: 9Citation - Scopus: 15Constraints on the Initial State of Pb-Pb Collisions Via Measurements of Z-Boson Yields and Azimuthal Anisotropy at Root S(nn)=5.02 Tev(Amer Physical Soc, 2021) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologyThe CMS experiment at the LHC has measured the differential cross sections of Z bosons decaying to pairs of leptons, as functions of transverse momentum and rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is compatible with zero, showing that Z bosons do not experience significant final-state interactions in the medium produced in the collision. Yields of Z bosons are compared to Glauber model predictions and are found to deviate from these expectations in peripheral collisions, indicating the presence of initial collision geometry and centrality selection effects. The precision of the measurement allows, for the first time, for a data-driven determination of the nucleon-nucleon integrated luminosity as a function of lead-lead centrality, thereby eliminating the need for its estimation based on a Glauber model.Article Citation - WoS: 152Citation - Scopus: 191Measurement of the Inelastic Proton-Proton Cross Section at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA measurement of the inelastic proton-proton cross section with the CMS detector at a center-of-mass energy of s=13 TeV is presented. The analysis is based on events with energy deposits in the forward calorimeters, which cover pseudorapidities of −6.6 < η < −3.0 and +3.0 < η < +5.2. An inelastic cross section of 68.6 ± 0.5(syst) ± 1.6(lumi) mb is obtained for events with MX> 4.1 GeV and/or MY> 13 GeV, where MX and MY are the masses of the diffractive dissociation systems at negative and positive pseudorapidities, respectively. The results are compared with those from other experiments as well as to predictions from high-energy hadron-hadron interaction models.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: 31Citation - Scopus: 60Search for Massive Resonances Decaying Into Ww, Wz, Zz, Qw, and Qz With Dijet Final States at $\sqrt{s} =$ 13 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyResults are presented from a search in the dijet final state for new massive narrow resonances decaying to pairs of W and Z bosons or to a W/Z boson and a quark. Results are based on data recorded in proton-proton collisions at s=13 TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 35.9 fb-1. The mass range investigated extends upwards from 1.2 TeV. No excess is observed above the estimated standard model background and limits are set at 95% confidence level on cross sections, which are interpreted in terms of various models that predict gravitons, heavy spin-1 bosons, and excited quarks. In a heavy vector triplet model, W′ and Z′ resonances, with masses below 3.2 and 2.7 TeV, respectively, and spin-1 resonances with degenerate masses below 3.8 TeV are excluded at 95% confidence level. In the case of a singlet W′ resonance masses between 3.3 and 3.6 TeV can be excluded additionally. Similarly, excited quark resonances, q∗, decaying to qW and qZ with masses less than 5.0 and 4.7 TeV, respectively, are excluded. In a narrow-width bulk graviton model, upper limits are set on cross sections ranging from 0.6 fb for high resonance masses above 3.6 TeV, to 36.0 fb for low resonance masses of 1.3 TeV.Article Citation - WoS: 15Citation - Scopus: 48Measurement of Normalized Differential T T ¯ Cross Sections in the Dilepton Channel From Pp Collisions at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyNormalized differential cross sections for top quark pair production are measured in the dilepton (e+e−, μ+μ−, and μ∓e±) decay channels in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurements are performed with data corresponding to an integrated luminosity of 2.1 fb−1 using the CMS detector at the LHC. The cross sections are measured differentially as a function of the kinematic properties of the leptons, jets from bottom quark hadronization, top quarks, and top quark pairs at the particle and parton levels. The results are compared to several Monte Carlo generators that implement calculations up to next-to-leading order in perturbative quantum chromodynamics interfaced with parton showering, and also to fixed-order theoretical calculations of top quark pair production up to next-to-next-to-leading order.Article Citation - WoS: 13Citation - Scopus: 14Search for Lepton-Flavor Violating Decays of Heavy Resonances and Quantum Black Holes To Eµ Final States in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA search is reported for heavy resonances decaying into eμ final states in proton-proton collisions recorded by the CMS experiment at the CERN LHC at s=13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The search focuses on resonance masses above 200 GeV. With no evidence found for physics beyond the standard model in the eμ mass spectrum, upper limits are set at 95% confidence level on the product of the cross section and branching fraction for this lepton-flavor violating signal. Based on these results, resonant τ sneutrino production in R-parity violating supersymmetric models is excluded for masses below 1.7 TeV, for couplings λ132 = λ231 = λ311′ = 0.01. Heavy Z′ gauge bosons with lepton-flavor violating transitions are excluded for masses up to 4.4 TeV. The eμ mass spectrum is also interpreted in terms of non-resonant contributions from quantum black-hole production in models with one to six extra spatial dimensions, and lower mass limits are found between 3.6 and 5.6 TeV. In all interpretations used in this analysis, the results of this search improve previous limits by about 1 TeV. These limits correspond to the most sensitive values obtained at colliders.Article Citation - WoS: 9Citation - Scopus: 26Search for Vectorlike Light-Flavor Quark Partners in Proton-Proton Collisions at S = 8 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA search is presented for heavy vectorlike quarks (VLQs) that couple only to light quarks in proton-proton collisions at s=8 TeV at the LHC. The data were collected by the CMS experiment during 2012 and correspond to an integrated luminosity of 19.7 fb-1. Both single and pair production of VLQs are considered. The single-production search is performed for down-type VLQs (electric charge of magnitude 1/3), while the pair-production search is sensitive to up-type (charge of magnitude 2/3) and down-type VLQs. Final states with at least one muon or one electron are considered. No significant excess over standard model expectations is observed, and lower limits on the mass of VLQs are derived. The lower limits range from 400 to 1800 GeV, depending on the single-production cross section and the VLQ branching fractions B to W, Z, and Higgs bosons. When considering pair production alone, VLQs with masses below 845 GeV are excluded for B(W)=1.0, and below 685 GeV for B(W)=0.5, B(Z)=B(H)=0.25. The results are more stringent than those previously obtained for single and pair production of VLQs coupled to light quarks.Article Citation - WoS: 97Citation - Scopus: 114Search for Higgs Boson Pair Production in Events With Two Bottom Quarks and Two Tau Leptons in Proton–proton Collisions at S=13tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA search for the production of Higgs boson pairs in proton–proton collisions at a centre-of-mass energy of 13 TeV is presented, using a data sample corresponding to an integrated luminosity of 35.9fb−1 collected with the CMS detector at the LHC. Events with one Higgs boson decaying into two bottom quarks and the other decaying into two τ leptons are explored to investigate both resonant and nonresonant production mechanisms. The data are found to be consistent, within uncertainties, with the standard model background predictions. For resonant production, upper limits at the 95% confidence level are set on the production cross section for Higgs boson pairs as a function of the hypothesized resonance mass and are interpreted in the context of the minimal supersymmetric standard model. For nonresonant production, upper limits on the production cross section constrain the parameter space for anomalous Higgs boson couplings. The observed (expected) upper limit at 95% confidence level corresponds to about 30 (25) times the prediction of the standard model.Article Citation - WoS: 11Citation - Scopus: 17Search for Pair Production of Excited Top Quarks in the Lepton + Jets Final State(Elsevier, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA search is performed for the pair production of spin-3/2 excited top quarks, each decaying to a top quark and a gluon. The search uses the data collected with the CMS detector from proton–proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Events are selected by requiring an isolated muon or electron, an imbalance in the transverse momentum, and at least six jets of which exactly two must be compatible with originating from the fragmentation of a bottom quark. No significant excess over the standard model predictions is found. A lower limit of 1.2 TeV is set at 95% confidence level on the mass of the spin-3/2 excited top quark in an extension of the Randall–Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. These are the best limits to date in a search for excited top quarks and the first at 13 TeV.Article Citation - WoS: 9Citation - Scopus: 17Measurement of Differential Cross Sections in the Kinematic Angular Variable ? * for Inclusive Z Boson Production in Pp Collisions at ?s=8 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyMeasurements of differential cross sections dσ/dϕ* and double-differential cross sections d2σ/dϕ*d|y| for inclusive Z boson production are presented using the dielectron and dimuon final states. The kinematic observable ϕ* correlates with the dilepton transverse momentum but has better resolution, and y is the dilepton rapidity. The analysis is based on data collected with the CMS experiment at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb−1. The normalised cross section (1/σ) dσ/dϕ*, within the fiducial kinematic region, is measured with a precision of better than 0.5% for ϕ* < 1. The measurements are compared to theoretical predictions and they agree, typically, within few percent.