Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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Browsing Mathematics / Matematik by Access Right "Attribution 3.0 United States"
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Article Citation - WoS: 76Citation - Scopus: 79Azimuthal Anisotropy of Charged Particles With Transverse Momentum Up To 100 Gev/C in Pbpb Collisions at ?snn=5.02 Tev(Elsevier Ltd., 2018-01) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyThe Fourier coefficients v2 and v3 characterizing the anisotropy of the azimuthal distribution of charged particles produced in PbPb collisions at sNN=5.02 TeV are measured with data collected by the CMS experiment. The measurements cover a broad transverse momentum range, 110 GeV/c range, where anisotropic azimuthal distributions should reflect the path-length dependence of parton energy loss in the created medium. Results are presented in several bins of PbPb collision centrality, spanning the 60% most central events. The v2 coefficient is measured with the scalar product and the multiparticle cumulant methods, which have different sensitivities to initial-state fluctuations. The values from both methods remain positive up to pT∼60–80 GeV/c, in all examined centrality classes. The v3 coefficient, only measured with the scalar product method, tends to zero for pT≳20 GeV/c. Comparisons between theoretical calculations and data provide new constraints on the path-length dependence of parton energy loss in heavy ion collisions and highlight the importance of the initial-state fluctuations.Article Citation - WoS: 29Citation - Scopus: 30Constraints on the Double-Parton Scattering Cross Section From Same-Sign W Boson Pair Production in Proton-Proton Collisions at ?s=8 Tev(Springer Verlag, 2018-02) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyA first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb−1. No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions.Article Citation - WoS: 54Citation - Scopus: 92Inclusive Search for a Highly Boosted Higgs Boson Decaying To a Bottom Quark-Antiquark Pair(American Physical Society, 2018-02) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyAn inclusive search for the standard model Higgs boson (H) produced with large transverse momentum (pT) and decaying to a bottom quark-antiquark pair (bb) is performed using a data set of pp collisions at s=13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb-1. A highly Lorentz-boosted Higgs boson decaying to bb is reconstructed as a single, large radius jet, and it is identified using jet substructure and dedicated b tagging techniques. The method is validated with Z→bb decays. The Z→bb process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of H→bb with reconstructed pT>450 GeV and in the pseudorapidity range -2.5<η<2.5 is 74±48(stat)-10+17(syst) fb, which is consistent within uncertainties with the standard model prediction. © 2018 CERN.Article Citation - WoS: 22Citation - Scopus: 31Measurement of the Lambda(b) Polarization and Angular Parameters in Lambda(b) -> J/Psi Lambda Decays From Pp Collisions at Root S=7 and 8 Tev(American Physical Society, 2018-04) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyAn analysis of the bottom baryon decay Λb→J/ψ(→μ+μ-)Λ(→pπ-) is performed to measure the Λb polarization and three angular parameters in data from pp collisions at s=7 and 8 TeV, collected by the CMS experiment at the Large Hadron Collider. The Λb polarization is measured to be 0.00±0.06(stat)±0.06(syst) and the parity-violating asymmetry parameter is determined to be 0.14±0.14(stat)±0.10(syst). The measurements are compared to various theoretical predictions, including those from perturbative quantum chromodynamics.Article Citation - WoS: 34Citation - Scopus: 41Measurements of Tt¯ Cross Sections in Association With B Jets and Inclusive Jets and Their Ratio Using Dilepton Final States in Pp Collisions at S=13tev(Elsevier Ltd., 2018-01) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyThe cross sections for the production of tt¯bb¯ and tt¯jj events and their ratio σtt¯bb¯/σtt¯jj are measured using data corresponding to an integrated luminosity of 2.3 fb−1collected in pp collisions at s=13 TeV with the CMS detector at the LHC. Events with two leptons (e or μ) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. In the full phase space, the measured ratio is 0.022±0.003(stat)±0.006(syst), the cross section σtt¯bb¯ is 4.0±0.6(stat)±1.3(syst) pb and σtt¯jj is 184±6(stat)±33(syst) pb. The measurements are compared with the standard model expectations obtained from a POWHEG simulation at next-to-leading-order interfaced with PYTHIA.Article Citation - WoS: 181Citation - Scopus: 284Observation of T¯th Production(American Physical Society, 2018-06) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyThe observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data at center-of-mass energies of s=7, 8, and 13 TeV, corresponding to integrated luminosities of up to 5.1, 19.7, and 35.9 fb-1, respectively. The data were collected with the CMS detector at the CERN LHC. The results of statistically independent searches for Higgs bosons produced in conjunction with a top quark-antiquark pair and decaying to pairs of W bosons, Z bosons, photons, τ leptons, or bottom quark jets are combined to maximize sensitivity. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance from the standard model for a Higgs boson mass of 125.09 GeV is 4.2 standard deviations. The combined best fit signal strength normalized to the standard model prediction is 1.26-0.26+0.31.Article Citation - WoS: 22Citation - Scopus: 24Pseudorapidity Distributions of Charged Hadrons in Proton-Lead Collisions at ?snn=5.02 and 8.16 Tev(Springer Verlag, 2018-01) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyThe pseudorapidity distributions of charged hadrons in proton-lead collisions at nucleon-nucleon center-of-mass energies sNN=5.02 and 8.16 TeV are presented. The measurements are based on data samples collected by the CMS experiment at the LHC. The number of primary charged hadrons produced in non-single-diffractive proton-lead collisions is determined in the pseudorapidity range |η lab | < 2.4. The charged-hadron multiplicity distributions are compared to the predictions from theoretical calculations and Monte Carlo event generators. In the center-of-mass pseudorapidity range |η cm | < 0.5, the average charged-hadron multiplicity densities 〈dN ch /dη cm 〉 |ηcm| < 0.5 are 17.31 ± 0.01 (stat) ± 0.59 (syst) and 20.10 ± 0.01 (stat) ± 0.85(syst) at sNN=5.02 and 8.16 TeV, respectively. The particle densities per participant nucleon are compared to similar measurements in proton-proton, proton-nucleus, and nucleus-nucleus collisions.Article Citation - WoS: 30Citation - Scopus: 32Search for Heavy Resonances Decaying To a Top Quark and a Bottom Quark in the Lepton+jets Final State in Proton–proton Collisions at 13 Tev(Elsevier Ltd., 2018-02) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyA search is presented for narrow heavy resonances decaying to a top quark and a bottom quark using data collected by the CMS experiment at s=13TeV in 2016. The data set analyzed corresponds to an integrated luminosity of 35.9fb−1. Final states that include a single lepton (e, μ), multiple jets, and missing transverse momentum are analyzed. No evidence is found for the production of a W′ boson, and the production of right-handed W′ bosons is excluded at 95% confidence level for masses up to 3.6TeV depending on the scenario considered. Exclusion limits for W′ bosons are also presented as a function of their coupling strength to left- and right-handed fermions. These limits on a W′ boson decaying via a top and a bottom quark are the most stringent published to date.Article Citation - WoS: 35Citation - Scopus: 93Search for Resonant and Nonresonant Higgs Boson Pair Production in the B B ¯final State in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2018-01) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologySearches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into , through either W or Z bosons, and b b ¯ are presented. The analyses are based on a sample of proton-proton collisions at s=13 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb −1 . Data and predictions from the standard model are in agreement within uncertainties. For the standard model HH hypothesis, the data exclude at 95% confidence level a product of the production cross section and branching fraction larger than 72 fb, corresponding to 79 times the standard model prediction. Constraints are placed on different scenarios considering anomalous couplings, which could affect the rate and kinematics of HH production. Upper limits at 95% confidence level are set on the production cross section of narrow-width spin-0 and spin-2 particles decaying to Higgs boson pairs, the latter produced with minimal gravity-like coupling.Article Citation - WoS: 3Citation - Scopus: 19Search for Supersymmetry in Events With at Least Three Electrons or Muons, Jets, and Missing Transverse Momentum in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2018-02) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyA search for new physics is carried out in events with at least three electrons or muons in any combination, jets, and missing transverse momentum. Results are based on the sample of proton-proton collision data produced by the LHC at a center-of-mass energy of 13 TeV and collected by the CMS experiment in 2016. The data sample analyzed corresponds to an integrated luminosity of 35.9 fb−1. Events are classified according to the number of b jets, missing transverse momentum, hadronic transverse momentum, and the invariant mass of same-flavor dilepton pairs with opposite charge. No significant excess above the expected standard model background is observed. Exclusion limits at 95% confidence level are computed for four different supersymmetric simplified models with pair production of gluinos or third-generation squarks. In the model with gluino pair production, with subsequent decays into a top quark-antiquark pair and a neutralino, gluinos with masses smaller than 1610 GeV are excluded for a massless lightest supersymmetric particle. In the case of bottom squark pair production, the bottom squark masses are excluded up to 840 GeV for charginos lighter than 200 GeV. For a simplified model of heavy top squark pair production, the t ˜ 2mass is excluded up to 720, 780, or 710 GeV for models with an exclusive t ˜ 2→ t ˜ 1H decay, an exclusive t ˜ 2→ t ˜ 1Z decay, or an equally probable mix of those two decays. In order to provide a simplified version of the analysis for easier interpretation, a small set of aggregate signal regions also has been defined, providing a compromise between simplicity and analysis sensitivityArticle Citation - WoS: 42Citation - Scopus: 35Search for Supersymmetry in Proton-Proton Collisions at 13 Tev Using Identified Top Quarks(American Physical Society, 2018-01) CMS Collaboration; Karapınar, Güler; 01. Izmir Institute of TechnologyA search for supersymmetry is presented based on proton-proton collision events containing identified hadronically decaying top quarks, no leptons, and an imbalance pTmiss in transverse momentum. The data were collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 35.9 fb-1. Search regions are defined in terms of the multiplicity of bottom quark jet and top quark candidates, the pTmiss, the scalar sum of jet transverse momenta, and the mT2 mass variable. No statistically significant excess of events is observed relative to the expectation from the standard model. Lower limits on the masses of supersymmetric particles are determined at 95% confidence level in the context of simplified models with top quark production. For a model with direct top squark pair production followed by the decay of each top squark to a top quark and a neutralino, top squark masses up to 1020 GeV and neutralino masses up to 430 GeV are excluded. For a model with pair production of gluinos followed by the decay of each gluino to a top quark-antiquark pair and a neutralino, gluino masses up to 2040 GeV and neutralino masses up to 1150 GeV are excluded. These limits extend previous results.