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: 34Citation - Scopus: 50Combined Searches for the Production of Supersymmetric Top Quark Partners in Proton-Proton Collisions at Root S=13 Tev(Springer, 2021) Karapınar, GülerA combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV.Article Citation - WoS: 15Citation - Scopus: 21Measurements of the Electroweak Diboson Production Cross Sections in Proton-Proton Collisions at Root S=5.02 Tev Using Leptonic Decays(American Physical Society, 2021) Karapınar, Güler; CMS CollaborationThe first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb(-1). Events with two, three, or four charged light leptons (electrons or muons) in the final state are analyzed. The WW, WZ, and ZZ total cross sections are measured as sigma(WW) = 37:0(-5.2)(+5.5) (stat)(-2.6)(+2.7) (syst) pb, sigma(WZ) = 6.4(-2.1)(+2.5) (stat)(-0.3)(+0.5)(syst) pb, and sigma(ZZ) = 5.3(-2.1)(+2.5)(stat)(-0.4)(+0.5) (syst) pb. All measurements are in good agreement with theoretical calculations at combined next-to-next-to-leading order quantum chromodynamics and next-to-leading order electroweak accuracy.Article Citation - WoS: 32Citation - Scopus: 42Search for Long-Lived Particles Decaying in the Cms End Cap Muon Detectors in Proton-Proton Collisions at Root S=13 Tev(American Physical Society, 2021) Karapınar, Güler; CMS CollaborationA search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb(-1) of proton-proton collisions at root s = 13 TeV, recorded at the LHC in 2016-2018. A novel technique is employed to reconstruct decays of LLPs in the end cap muon detectors. The search is sensitive to a broad range of LLP decay modes and to masses as low as a few GeV. No excess of events above the SM background is observed. The most stringent limits to date on the branching fraction of the Higgs boson to LLPs subsequently decaying to quarks and tau(+)tau(-) are found for proper decay lengths greater than 6, 20, and 40 m, for LLP masses of 7, 15, and 40 GeV, respectively.Article Citation - WoS: 27Citation - Scopus: 31Development and Validation of Herwig 7 Tunes From Cms Underlying-Event Measurements(Springer, 2021) Karapınar, GülerThis paper presents new sets of parameters (tunes) for the underlying-event model of the herwig 7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in herwig 7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at v s = 0.9, 7, and 13 TeV. The tunes are based on the NNPDF3.1 next-to-nextto-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-nextto-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and forminimum-bias, inclusive jet, top quark pair, and Zand Wboson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the data.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; CMS CollaborationThe 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: 33Measurement of the Top-Quark Mass in All-Jets T(t)over-Bar Events in Pp Collisions at ?s=7 Tev(Springer Verlag, 2014) Karapınar, Güler; CMS CollaborationThe mass of the top quark is measured using a sample of t (t) over bar candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at root s = 7 TeV in 2011 and corresponds to an integrated luminosity of 3.54 fb(-1). The mass is reconstructed for each event employing a kinematic fit of the jets to a t (t) over bar hypothesis. The top-quark mass is measured to be 173.49 +/- 0.69 ( stat.) +/- 1.21 ( syst.) GeV. A combination with previously published measurements in other decay modes byCMSyields a mass of 173.54 +/- 0.33 (stat.) +/- 0.96 (syst.) GeV.Article Citation - WoS: 162Search for Invisible Decays of Higgs Bosons in the Vector Boson Fusion and Associated Zh Production Modes(Springer Verlag, 2014) Karapınar, Güler; CMS CollaborationA search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a bb quark pair. The searches use the 8TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 fb(-1). Certain channels include data from 7TeV collisions corresponding to an integrated luminosity of 4.9 fb(-1).The searches are sensitive to non-standardmodel invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at m(H) = 125GeV is found to be 0.58 (0.44) at 95% confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.Article Citation - WoS: 230Searches for Electroweak Production of Charginos, Neutralinos, and Sleptons Decaying To Leptons and W, Z, and Higgs Bosons in Pp Collisions at 8 Tev(Springer Verlag, 2014) Karapınar, Güler; CMS CollaborationSearches for the direct electroweak production of supersymmetric charginos, neutralinos, and sleptons in a variety of signatures with leptons and W, Z, and Higgs bosons are presented. Results are based on a sample of proton-proton collision data collected at center-of-mass energy root s = 8 TeV with the CMS detector in 2012, corresponding to an integrated luminosity of 19.5 fb(-1). The observed event rates are in agreement with expectations from the standard model. These results probe charginos and neutralinos with masses up to 720 GeV, and sleptons up to 260 GeV, depending on the model details.Article Citation - WoS: 312Observation of the Diphoton Decay of the Higgs Boson and Measurement of Its Properties(Springer Verlag, 2014) Karapınar, Güler; CMS CollaborationObservation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions during the 2011 and 2012 LHC running periods. The data samples correspond to integrated luminosities of 5.1 fb(-1) at root s = 7 TeV and 19.7 fb(-1) at 8 TeV. A clear signal is observed in the diphoton channel at a mass close to 125 GeV with a local significance of 5.7 sigma, where a significance of 5.2 sigma is expected for the standard model Higgs boson. The mass is measured to be 124.70 +/- 0.34 GeV = 124.70 +/- 0.31 (stat) +/- 0.15 (syst) GeV, and the best-fit signal strength relative to the standard model prediction is 1.14(-0.23)(+0.26) = 1.14 +/- 0.21 (stat) (-0.05)(+0.09) (syst) (+0.13)(-0.09) (theo). Additional measurements include the signal strength modifiers associated with different production mechanisms, and hypothesis tests between spin-0 and spin-2 models.Article Citation - WoS: 80Citation - Scopus: 74Measurements of Differential and Double-Differential Drell-Yan Cross Sections in Proton-Proton Collisions at ?s=8 Tev(Springer Verlag, 2015) Karapınar, Güler; CMS CollaborationMeasurements of the differential and double-differential Drell-Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton-proton collision data at root s = 8 TeV recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb(-1). The measured inclusive cross section in the Z peak region (60-120 GeV), obtained from the combination of the dielectron and dimuon channels, is 1138 +/- 8 (exp) +/- 25 (theo) +/- 30 (lumi) pb, where the statistical uncertainty is negligible. The differential cross section d sigma/dm in the dilepton mass range 15-2000 GeV is measured and corrected to the full phase space. The double-differential cross section d(2)sigma/dm d vertical bar y vertical bar is also measured over the mass range 20 to 1500 GeV and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at root s = 7 and 8 TeV are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with FEWZ 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs.