Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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Article Citation - WoS: 34Citation - Scopus: 40Search for Single Production of Vector-Like Quarks Decaying To a B Quark and a Higgs Boson(Springer Verlag, 2019) Karapınar, GülerA search is presented for single production of heavy vector-like quarks (B) that decay to a Higgs boson and a b quark, with the Higgs boson decaying to a highly boosted b b ¯ pair reconstructed as a single collimated jet. The analysis is based on data collected by the CMS experiment in proton-proton collisions at s=13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The data are consistent with background expectations, and upper limits at 95% confidence level on the product of the B quark cross section and the branching fraction are obtained in the range 1.28–0.07 pb, for a narrow B quark with a mass between 700 and 1800 GeV. The production of B quarks with widths of 10, 20 and 30% of the resonance mass is also considered, and the sensitivities obtained are similar to those achieved in the narrow width case. This is the first search at the CERN LHC for the single production of a B quark through its fully hadronic decay channel, and the first study considering finite resonance widths of the B quark.Article Citation - WoS: 1Citation - Scopus: 1Search for Natural Supersymmetry in Events With Top Quark Pairs and Photons in Pp Collisions at ?s=8 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerResults are presented from a search for natural gauge-mediated supersymmetry (SUSY) in a scenario in which the top squark is the lightest squark, the next-to-lightest SUSY particle is a bino-like neutralino, and the lightest SUSY particle is the gravitino. The strong production of top squark pairs can produce events with pairs of top quarks and neutralinos, with each bino-like neutralino decaying to a photon and a gravitino. The search is performed using a sample of pp collision data accumulated by the CMS experiment at s=8 TeV, corresponding to an integrated luminosity of 19.7 fb−1. The final state consists of a lepton (electron or muon), jets, and one or two photons. The imbalance in transverse momentum in the events is compared with the expected spectrum from standard model processes. No excess event yield is observed beyond the expected background, and the result is interpreted in the context of a general model of gauge-mediated SUSY breaking that leads to exclusion of top squark masses below 650–730 GeV.Article Citation - WoS: 25Citation - Scopus: 37Measurements of Jet Charge With Dijet Events in Pp Collisions at ?s=8 Tev(Springer Verlag, 2017) CMS Collaboration; Karapınar, GülerJet charge is an estimator of the electric charge of a quark, antiquark, or gluon initiating a jet. It is based on the momentum-weighted sum of the electric charges of the jet constituents. Measurements of three charge observables of the leading jet in transverse momentum pT are performed with dijet events. The analysis is carried out with ata collected by the CMS experiment at the CERN LHC in proton-proton collisions at s=8 TeV corresponding to an integrated luminosity of 19.7fb−1. The results are presented as a function of the pT of the leading jet and compared to predictions from leading- and next-to-leading-order event generators combined with parton showers. Measured jet charge distributions, unfolded for detector effects, are reported, which expand on previous measurements of the jet charge average and standard deviation in pp collisions.Article Citation - WoS: 16Citation - Scopus: 44Search for New Physics in the Monophoton Final State in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2017) CMS Collaboration; Karapınar, GülerA search is conducted for new physics in a final state containing a photon and missing transverse momentum in proton-proton collisions at s=13 TeV. The data collected by the CMS experiment at the CERN LHC correspond to an integrated luminosity of 12.9 fb−1. No deviations are observed relative to the predictions of the standard model. The results are interpreted as exclusion limits on the dark matter production cross sections and parameters in models containing extra spatial dimensions. Improved limits are set with respect to previous searches using the monophoton final state. In particular, the limits on the extra dimension model parameters are the most stringent to date in this channelOther Citation - WoS: 13Citation - Scopus: 9Erratum To: Search for New Physics in Events With Same-Sign Dileptons and Jets in Pp Collisions at ?s=8 Tev(Springer Verlag, 2015) CMS Collaboration; Karapınar, GülerA search for new physics is performed based on events with jets and a pair of isolated, same-sign leptons. The results are obtained using a sample of proton-proton collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV at the LHC, corresponding to an integrated luminosity of 19.5 fb-1. In order to be sensitive to a wide variety of possible signals beyond the standard model, multiple search regions defined by the missing transverse energy, the hadronic energy, the number of jets and b-quark jets, and the transverse momenta of the leptons in the events are considered. No excess above the standard model background expectation is observed and constraints are set on a number of models for new physics, as well as on the same-sign top-quark pair and quadruple-top-quark production cross sections. Information on event selection efficiencies is also provided, so that the results can be used to confront an even broader class of new physics models.Article Citation - WoS: 42Citation - Scopus: 40Search for a Light Charged Higgs Boson Decaying To Cs¯ in Pp Collisions at ?s=8 Tev(Springer Verlag, 2015) CMS Collaboration; Karapınar, GülerA search for a light charged Higgs boson, originating from the decay of a top quark and subsequently decaying into a charm quark and a strange antiquark, is presented. The data used in the analysis correspond to an integrated luminosity of 19.7 fb−1 recorded in proton-proton collisions at (formula presented.) TeV by the CMS experiment at the LHC. The search is performed in the process tt¯→W±bH∓b¯(formula presented.), where the W boson decays to a lepton (electron or muon) and a neutrino. The decays lead to a final state comprising an isolated lepton, at least four jets and large missing transverse energy. No significant deviation is observed in the data with respect to the standard model predictions, and model-independent upper limits are set on the branching fraction ℬt→(formula presented.), ranging from 1.2 to 6.5% for a charged Higgs boson with mass between 90 and 160 GeV, under the assumption that ℬH+→(formula presented.)[Figure not available: see fulltext.] © 2015, The Author(s).Article Citation - WoS: 22Citation - Scopus: 36Search for W'›tb Decays in the Lepton + Jets Final State in Pp Collisions at ?s = 8tev(Springer Verlag, 2014) CMS Collaboration; Karapınar, GülerResults are presented from a search for the production of a heavy gauge boson W′ decaying into a top and a bottom quark, using a data set collected by the CMS experiment at √s = 8TeV and corresponding to an integrated luminosity of 19.5 fb−1. Various models of W′-boson production are studied by allowing for an arbitrary combination of left-and right-handed couplings. The analysis is based on the detection of events with a lepton (e, μ), jets, and missing transverse energy in the final state. No evidence for W′-boson production is found and 95% confidence level upper limits on the production cross section times branching fraction are obtained. For W′ bosons with purely right-handed couplings, and for those with left-handed couplings assuming no interference effects, the observed 95% confidence level limit is M(W′) > 2.05TeV. For W′ bosons with purely left handed couplings, including interference effects, the observed 95% confidence level limit is M(W′) > 1.84TeV. The results presented in this paper are the most stringent limits published to date.Article Citation - WoS: 57Citation - Scopus: 92Measurement of Prompt J/? Pair Production in Pp Collisions at S = 7 Tev(Springer Verlag, 2014) CMS Collaboration; Karapınar, GülerProduction of prompt J/ψ meson pairs in proton-proton collisions at s = 7 TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 fb-1. The two J/ψ mesons are fully reconstructed via their decays into μ +μ -pairs. This observation provides for the first time access to the high-transverse-momentum region of J/ψ pair production where model predictions are not yet established. The total and differential cross sections are measured in a phase space defined by the individual J/ψ transverse momentum (p T J/ψ) and rapidity (|y J/ψ|): |y J/ψ| < 1.2 for p T J/ψ> 6.5 GeV/c; 1.2 < |y J/ψ| < 1.43 for a p Tthreshold that scales linearly with |y J/ψ| from 6.5 to 4.5 GeV/c; and 1.43 < |y J/ψ| < 2.2 for p T J/ψ> 4.5 GeV/c. The total cross section, assuming unpolarized prompt J/ψ pair production is 1.49 ± 0.07 (stat) ±0.13 (syst) nb. Different assumptions about the J/ψ polarization imply modifications to the cross section ranging from -31% to +27%. [Figure not available: see fulltext.] © 2014 The Author(s).Article Citation - WoS: 58Citation - Scopus: 86Search for Heavy Quarks Decaying Into a Top Quark and a W or Z Boson Using Lepton + Jets Events in Pp Collisions at ?s = 7 Tev(Springer Verlag, 2013) CMS Collaboration; Karapınar, GülerResults are presented from a search for the pair-production of heavy quarks, QQ̄, that decay exclusively into a top quark and a W or Z boson. The search is performed using a sample of proton-proton collisions at √s = 7 TeV corresponding to an integrated luminosity of 5.0 fb-1, collected by the Compact Muon Solenoid experiment. The signal region is defined using a sample of events containing one electron or muon, missing transverse momentum, and at least four jets with large transverse momenta, where one jet is likely to originate from the decay of a bottom quark. No significant excess of events is observed with respect to the standard model expectations. Assuming a strong pair-production mechanism, quark masses below 675 (625) GeV decaying into tW (tZ) are excluded at the 95 % confidence level.[Figure not available: see fulltext.] © 2013 CERN for the benefit of the CMS collaboration.Article Citation - WoS: 99Citation - Scopus: 101Measurement of the X(3872) Production Cross Section Via Decays To J/??+?- in Pp Collisions at ?s = 7 Tev(Springer Verlag, 2013) CMS Collaboration; Karapınar, GülerThe production of the X(3872) is studied in pp collisions at √s = 7TeV, using decays to J/ψπ+π−, where the J/ψ decays to two muons. The data were recorded by the CMS experiment and correspond to an integrated luminosity of 4.8fb−1. The measurements are performed in a kinematic range in which the X(3872) candidates have a transverse momentum 10 < pT < 50GeV and rapidity |y| < 1.2. The ratio of the X(3872) and ψ (2S) cross sections times their branching fractions into J/ψπ+π− is measured as a function of pT. In addition, the fraction of X(3872) originating from B decays is determined. From these measurements the prompt X(3872) differential cross section times branching fraction as a function of pT is extracted. The π+π− mass spectrum of the J/ψπ+π− system in the X(3872) decays is also investigated. © 2013, Springer Verlag. All rights reserved.