Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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Article Citation - WoS: 24Citation - Scopus: 34Measurement of Spin Correlations in Tt‾ Production Using the Matrix Element Method in the Muon+jets Final State in Pp Collisions at √s=8 Tev(Elsevier B.V., 2016) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Cuevas, J.; 01. Izmir Institute of TechnologyThe consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb−1. The data are compared with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72±0.08(stat)−0.13 +0.15(syst), representing the most precise measurement of this quantity in the muon+jets final state to date. © 2016 The AuthorArticle Citation - WoS: 34Citation - Scopus: 37Search for a Low-Mass Pseudoscalar Higgs Boson Produced in Association With a Bb‾ Pair in Pp Collisions at √s=8 Tev(Elsevier B.V., 2016) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Fernandez Menendez, J.; 01. Izmir Institute of TechnologyA search is reported for a light pseudoscalar Higgs boson decaying to a pair of τ leptons, produced in association with a bb‾ pair, in the context of two-Higgs-doublet models. The results are based on pp collision data at a centre-of-mass energy of 8 TeV collected by the CMS experiment at the LHC and corresponding to an integrated luminosity of 19.7 fb−1. Pseudoscalar boson masses between 25 and 80 GeV are probed. No evidence for a pseudoscalar boson is found and upper limits are set on the product of cross section and branching fraction to τ pairs between 7 and 39 pb at the 95% confidence level. This excludes pseudoscalar A bosons with masses between 25 and 80 GeV, with SM-like Higgs boson negative couplings to down-type fermions, produced in association with bb‾ pairs, in Type II, two-Higgs-doublet models. © 2016 The Author(s)Article Citation - WoS: 40Citation - Scopus: 41Search for Supersymmetry in the Multijet and Missing Transverse Momentum Final State in Pp Collisions at 13 Tev(Elsevier B.V., 2016) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Castineiras De Saa, J.R.; 01. Izmir Institute of TechnologyA search for new physics is performed based on all-hadronic events with large missing transverse momentum produced in proton–proton collisions at s=13 TeV. The data sample, corresponding to an integrated luminosity of 2.3 fb−1, was collected with the CMS detector at the CERN LHC in 2015. The data are examined in search regions of jet multiplicity, tagged bottom quark jet multiplicity, missing transverse momentum, and the scalar sum of jet transverse momenta. The observed numbers of events in all search regions are found to be consistent with the expectations from standard model processes. Exclusion limits are presented for simplified supersymmetric models of gluino pair production. Depending on the assumed gluino decay mechanism, and for a massless, weakly interacting, lightest neutralino, lower limits on the gluino mass from 1440 to 1600 GeV are obtained, significantly extending previous limits. © 2016 The AuthorArticle Citation - WoS: 149Citation - Scopus: 196Angular Analysis of the Decay B0 → K⁎0μ+μ− From Pp Collisions at √s=8 Tev(Elsevier B.V., 2016) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Puerta Pelayo, J.; 01. Izmir Institute of TechnologyThe angular distributions and the differential branching fraction of the decay B0→K⁎(892)0μ+μ− are studied using data corresponding to an integrated luminosity of 20.5 fb−1 collected with the CMS detector at the LHC in pp collisions at s=8 TeV. From 1430 signal decays, the forward–backward asymmetry of the muons, the K⁎(892)0 longitudinal polarization fraction, and the differential branching fraction are determined as a function of the dimuon invariant mass squared. The measurements are among the most precise to date and are in good agreement with standard model predictions. © 2015 CERN for the benefit of the CMS CollaborationArticle Citation - WoS: 29Citation - Scopus: 33Measurement of the Cross Section Ratio Σtt¯bb¯/Σtt¯jj in Pp Collisions at S=8 Tev(Elsevier B.V., 2015) Karapınar, Güler; Karapınar, Güler; Bergauer, T.; Dragicevic, M.; Malgeri, L.; Tumasyan, A.; 01. Izmir Institute of TechnologyThe first measurement of the cross section ratio σtt¯bb¯/σtt¯jj is presented using a data sample corresponding to an integrated luminosity of 19.6 fb−1 collected in pp collisions at s=8 TeV with the CMS detector at the LHC. Events with two leptons (e or μ) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum pT of both 20 and 40 GeV/c. The measured ratio is 0.022±0.003(stat)±0.005(syst) for pT>20 GeV/c. The absolute cross sections σtt¯bb¯ and σtt¯jj are also measured. The measured ratio for pT>40 GeV/c is compatible with a theoretical quantum chromodynamics calculation at next-to-leading order. © 2015 CERN for the benefit of the CMS CollaborationArticle Citation - WoS: 131Citation - Scopus: 144Search for Diphoton Resonances in the Mass Range From 150 To 850 Gev in Pp Collisions at S=8tev(Elsevier B.V., 2015) Khachatryan, V.; Karapınar, Güler; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; de Trocöniz, J.F.; 01. Izmir Institute of TechnologyResults are presented of a search for heavy particles decaying into two photons. The analysis is based on a 19.7fb−1 sample of proton–proton collisions at s=8TeV collected with the CMS detector at the CERN LHC. The diphoton mass spectrum from 150 to 850GeV is used to search for an excess of events over the background. The search is extended to new resonances with natural widths of up to 10% of the mass value. No evidence for new particle production is observed and limits at 95% confidence level on the production cross section times branching fraction to diphotons are determined. These limits are interpreted in terms of two-Higgs-doublet model parameters. © 2015 CERN for the benefit of the CMS Collaboration