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: 27Citation - Scopus: 31Development and Validation of Herwig 7 Tunes From Cms Underlying-Event Measurements(Springer, 2021) Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyThis 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; 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: 35Citation - Scopus: 39Search for Top Squark Pair Production Using Dilepton Final States in Pp Collision Data Collected at Root S=13tev(Springer, 2021) CMS Collaboration; Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyA search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from bquarks, and missing transverse momentum. The search uses data from proton-proton collisions at root s = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 137 fb(-1). Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at 95% confidence level on the masses of the top squark and the neutralino up to 925 and 450 GeV, respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850 GeV for neutralino masses below 420 GeV. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4 TeV and 900 GeV respectively for the top squark and the lightest neutralino.Article Citation - WoS: 72Search for a Standard-Model Higgs Boson With a Mass in the Range 145 To 1000 Gev at the Lhc(Springer Verlag, 2013) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologyA search for a standard-model-like Higgs boson in the H -> WW and H -> ZZ decay channels is reported, for Higgs boson masses in the range 145 < m(H) < 1000 GeV. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 fb(-1) at root s = 7 TeV and up to 5.3 fb(-1) at root s = 8 TeV, recorded by the CMS experiment at the LHC. The combined upper limits at 95 % confidence level on products of the cross section and branching fractions exclude a standard-model-like Higgs boson in the range 145 < m(H) < 710 GeV, thus extending the mass region excluded by CMS from 127-600 GeV up to 710 GeV.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; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologyThe 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; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologyA 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; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologySearches 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; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologyObservation 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: 38Measurement of Electroweak Production of Two Jets in Association With a Z Boson in Proton-Proton Collisions at ?s=8 Tev(Springer Verlag, 2015) Karapınar, Güler; Karapınar, Güler; CMS Collaboration; 01. Izmir Institute of TechnologyThe purely electroweak (EW) cross section for the production of two jets in association with a Z boson, in proton-proton collisions at root s = 8 TeV, is measured using data recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 19.7 fb(-1). The electroweak cross section for the lljj final state (with l = e or mu and j representing the quarks produced in the hard interaction) in the kinematic region defined by M-ll > 50 GeV, M-jj > 120 GeV, transverse momentum p(Tj) > 25 GeV, and pseudorapidity vertical bar eta(j)vertical bar < 5, is found to be sigma(EW) (lljj) = 174 +/- 15 (stat) +/- 40 (syst) fb, in agreement with the standard model prediction. The associated jet activity of the selected events is studied, in particular in a signal-enriched region of phase space, and the measurements are found to be in agreement with QCD predictions.Article Citation - WoS: 66Measurement of the Inclusive 3-Jet Production Differential Cross Section in Proton-Proton Collisions at 7 Tev and Determination of the Strong Coupling Constant in the Tev Range(Springer Verlag, 2015) Karapınar, Güler; Karapınar, Güler; 01. Izmir Institute of TechnologyThis paper presents a measurement of the inclusive 3-jet production differential cross section at a proton-proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity of 5 fb(-1) collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445-3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to the strong coupling constant alpha(S) is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of alpha(S)(M-Z) = 0.1171 +/- 0.0013 (exp) (+0.0073)(-0.0047) (theo).