WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 8Citation - Scopus: 49Measurement of the Inclusive and Differential Higgs Boson Production Cross Sections in the Leptonic Ww Decay Mode at P Root S=13 Tev(Springer, 2021) CMS Collaboration; Karapınar, GülerMeasurements of the fiducial inclusive and differential production cross sections of the Higgs boson in proton-proton collisions at root s = 13 TeV are performed using events where the Higgs boson decays into a pair of W bosons that subsequently decay into a final state with an electron, a muon, and a pair of neutrinos. The analysis is based on data collected with the CMS detector at the LHC during 2016-2018, corresponding to an integrated luminosity of 137 fb(-1). Production cross sections are measured as a function of the transverse momentum of the Higgs boson and the associated jet multiplicity. The Higgs boson signal is extracted and simultaneously unfolded to correct for selection efficiency and resolution effects using maximum-likelihood fits to the observed distributions in data. The integrated fiducial cross section is measured to be 86.5 +/- 9.5 fb, consistent with the Standard Model expectation of 82.5 +/- 4.2 fb. No significant deviation from the Standard Model expectations is observed in the differential measurements.Article Citation - WoS: 250Evidence for the 125 Gev Higgs Boson Decaying To a Pair of Tau Leptons(Springer Verlag, 2014) Karapınar, GülerA search for a standard model Higgs boson decaying into a pair of tau leptons is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. The dataset corresponds to an integrated luminosity of 4.9 fb(-1) at a centre-of-mass energy of 7 TeV and 19.7 fb(-1) at 8 TeV. Each tau lepton decays hadronically or leptonically to an electron or a muon, leading to six different final states for the tau-lepton pair, all considered in this analysis. An excess of events is observed over the expected background contributions, with a local significance larger than 3 standard deviations for m (H) values between 115 and 130 GeV. The best fit of the observed H -> tau tau signal cross section times branching fraction for m(H) = 125 GeV is 0.78 +/- 0.27 times the standard model expectation. These observations constitute evidence for the 125 GeV Higgs boson decaying to a pair of tau leptons.Article Citation - WoS: 180Citation - Scopus: 112Search for Neutral Mssm Higgs Bosons Decaying To a Pair of Tau Leptons in Pp Collisions(Springer Verlag, 2014) Karapınar, Güler; Demir, Durmuş AliA search for neutral Higgs bosons in the minimal supersymmetric extension of the standard model (MSSM) decaying to tau-lepton pairs in pp collisions is performed, using events recorded by the CMS experiment at the LHC. The dataset corresponds to an integrated luminosity of 24.6 fb(-1), with 4.9 fb(-1) at 7TeV and 19.7 fb(-1) at 8TeV. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes the case where the Higgs boson is produced in association with a b-quark jet. No excess is observed in the tau-lepton-pair invariant mass spectrum. Exclusion limits are presented in the MSSM parameter space for different benchmark scenarios, m(h)(max), m(h)(mod+), m(h)(mod-), light-stop, light-stau, T-phobic, and low-m(H). Upper limits on the cross section times branching fraction for gluon fusion and b-quark associated Higgs boson production are also given.Article Citation - WoS: 22Citation - Scopus: 103Search for Heavy Higgs Bosons Decaying To a Top Quark Pair in Proton-Proton Collisions at Root S=13 Tev(Springer Verlag, 2020) ; CMS Collaboration; Karapınar, GülerA search is presented for additional scalar (H) or pseudoscalar (A) Higgs bosons decaying to a top quark pair in proton-proton collisions at a center-of-mass energy of 13 TeV. The data set analyzed corresponds to an integrated luminosity of 35.9 fb(-1) collected by the CMS experiment at the LHC. Final states with one or two charged leptons are considered. The invariant mass of the reconstructed top quark pair system and variables that are sensitive to the spin of the particles decaying into the top quark pair are used to search for signatures of the H or A bosons. The interference with the standard model top quark pair background is taken into account. A moderate signal-like deviation compatible with an A boson with a mass of 400 GeV is observed with a global significance of 1.9 standard deviations. New stringent constraints are reported on the strength of the coupling of the hypothetical bosons to the top quark, with the mass of the bosons ranging from 400 to 750 GeV and their total relative width from 0.5 to 25%. The results of the search are also interpreted in a minimal supersymmetric standard model scenario. Values of m(A) from 400 to 700 GeV are probed, and a region with values of tan beta below 1.0 to 1.5, depending on m(A), is excluded at 95% confidence level.Article Citation - WoS: 26Citation - Scopus: 46Search for a Light Pseudoscalar Higgs Boson in the Boosted Mu Mu Tau Tau Final State in Proton-Proton Collisions at Root S=13 Tev(Springer Verlag, 2020) Karapınar, GülerA search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H -> aa -> mu mu tau tau, and considers pseudoscalar masses in the range 3.6 < m(a) < 21 GeV. Because of the large mass difference between the H and the a bosons and the small masses of the a boson decay products, both the mu mu and the tau tau pairs have high Lorentz boost and are collimated. The tau tau reconstruction efficiency is increased by modifying the standard technique for hadronic tau lepton decay reconstruction to account for a nearby muon. No significant signal is observed. Model-independent limits are set at 95% confidence level, as a function of m(a), on the branching fraction (B) for H -> aa -> mu mu tau tau, down to 1.5 (2.0)x10(-4) for m(H) = 125 (300) GeV. Model-dependent limits on B(H -> aa) are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV.Article Citation - WoS: 4Citation - Scopus: 8Search for Decays of the 125 Gev Higgs Boson Into a Z Boson and a Rho or Phi Meson(Springer Verlag, 2020) CMS Collaboration; Karapınar, GülerDecays of the 125 GeV Higgs boson into a Z boson and a rho (0)(770) or (1020) meson are searched for using proton-proton collision data collected by the CMS experiment at the LHC at <mml:msqrt>s</mml:msqrt> = 13 TeV. The analysed data set corresponds to an integrated luminosity of 137 fb(-1). Events are selected in which the Z boson decays into a pair of electrons or a pair of muons, and the rho and phi mesons decay into pairs of pions and kaons, respectively. No significant excess above the background model is observed. As different polarization states are possible for the decay products of the Z boson and rho or phi mesons, affecting the signal acceptance, scenarios in which the decays are longitudinally or transversely polarized are considered. Upper limits at the 95% confidence level on the Higgs boson branching fractions into Z rho and Z phi are determined to be 1.04-1.31% and 0.31-0.40%, respectively, where the ranges reflect the considered polarization scenarios; these values are 740-940 and 730-950 times larger than the respective standard model expectations. These results constitute the first experimental limits on the two decay channels.Article Citation - WoS: 27Citation - Scopus: 48Search for the Decay of a Higgs Boson in the Ll Gamma Channel in Proton-Proton Collisions at Root S=13 Tev(Springer Verlag, 2018) Karapınar, GülerA search for a Higgs boson decaying into a pair of electrons or muons and a photon is described. Higgs boson decays to a Z boson and a photon (H Z , = e or ), or to two photons, one of which has an internal conversion into a muon pair (H (*) ) were considered. The analysis is performed using a data set recorded by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). No significant excess above the background prediction has been found. Limits are set on the cross section for a standard model Higgs boson decaying to opposite-sign electron or muon pairs and a photon. The observed limits on cross section times the corresponding branching fractions vary between 1.4 and 4.0 (6.1 and 11.4) times the standard model cross section for H (*) (H Z ) in the 120-130 GeV mass range of the system. The H (*) and H Z analyses are combined for m(H) =125GeV, obtaining an observed (expected) 95% confidence level upper limit of 3.9 (2.0) times the standard model cross section.Article Citation - WoS: 62Citation - Scopus: 116Measurements of Higgs Boson Properties in the Diphoton Decay Channel in Proton-Proton Collisions at Root S=13 Tev(Springer Verlag, 2018) Karapınar, Güler; CMS CollaborationMeasurements of Higgs boson properties in the H decay channel are reported. The analysis is based on data collected by the CMS experiment in proton-proton collisions at =13 TeV during the 2016 LHC running period, corresponding to an integrated luminosity of 35.9 fb(-1). Allowing the Higgs mass to float, the measurement yields a signal strength relative to the standard model prediction of 1.18-0.14+0.17=1.18-0.11+0.12(stat)-0.07+0.09(syst)-0.06+0.07(theo), which is largely insensitive to the exact Higgs mass around 125 GeV. Signal strengths associated with the different Higgs boson production mechanisms, couplings to bosons and fermions, and effective couplings to photons and gluons are also measured.Article Citation - WoS: 26Citation - Scopus: 27Search for Heavy Resonances Decaying Into Two Higgs Bosons or Into a Higgs Boson and a W or Z Boson in Proton-Proton Collisions at 13 Tev(Springer Verlag, 2019) Karapınar, Güler; CMS CollaborationA search is presented for massive narrow resonances decaying either into two Higgs bosons, or into a Higgs boson and a W or Z boson. The decay channels considered are HHbb+- and VHqq-, where H denotes the Higgs boson, and V denotes the W or Z boson. This analysis is based on a data sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV by the CMS Collaboration, corresponding to an integrated luminosity of 35.9 fb(-1). For the TeV-scale mass resonances considered, substructure techniques provide ways to differentiate among the hadronization products from vector boson decays to quarks, Higgs boson decays to bottom quarks, and quark- or gluon-induced jets. Reconstruction techniques are used that have been specifically optimized to select events in which the tau lepton pair is highly boosted. The observed data are consistent with standard model expectations and upper limits are set at 95% confidence level on the product of cross section and branching fraction for resonance masses between 0.9 and 4.0 TeV. Exclusion limits are set in the context of bulk radion and graviton models:spin-0 radion resonances are excluded below a mass of 2.7 TeV at 95% confidence level. In the spin-1 heavy vector triplet framework, mass-degenerate W and Z resonances with dominant couplings to the standard model gauge bosons are excluded below a mass of 2.8 TeV at 95% confidence level. These are the first limits for massive resonances at the TeV scale with these decay channels at 13 TeV.Article Citation - WoS: 8Citation - Scopus: 22Search for a Low-Mass Tau(-)tau(+) Resonance in Association With a Bottom Quark in Proton-Proton Collisions at Root S=13 Tev(Springer Verlag, 2019) Karapınar, Güler; CMS CollaborationA general search is presented for a low-mass (-+) resonance produced in association with a bottom quark. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb(-1). The data are consistent with the standard model expectation. Upper limits at 95% confidence level on the cross section times branching fraction are determined for two signal models: a light pseudoscalar Higgs boson decaying to a pair of leptons produced in association with bottom quarks, and a low-mass boson X decaying to a -lepton pair that is produced in the decay of a bottom-like quark B such that B bX. Masses between 25 and 70 GeV are probed for the light pseudoscalar boson with upper limits ranging from 250 to 44 pb. Upper limits from 20 to 0.3 pb are set on B masses between 170 and 450 GeV for X boson masses between 20 and 70 GeV.