Rectorate / Rektörlük
Permanent URI for this collectionhttps://hdl.handle.net/11147/6849
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Article Citation - WoS: 21Citation - Scopus: 25Search for a Heavy Vector Resonance Decaying To a Z Boson and a Higgs Boson in Proton-Proton Collisions at <mml:msqrt>s</Mml:msqrt>=13 Te(Springer, 2021) CMS Collaboration; Karapınar, GülerA search is presented for a heavy vector resonance decaying into a Z boson and the standard model Higgs boson, where the Z boson is identified through its leptonic decays to electrons, muons, or neutrinos, and the Higgs boson is identified through its hadronic decays. The search is performed in a Lorentz-boosted regime and is based on data collected from 2016 to 2018 at the CERN LHC, corresponding to an integrated luminosity of 137 fb-1. Upper limits are derived on the production of a narrow heavy resonance Z ', and a mass below 3.5 and 3.7 Te is excluded at 95% confidence level in models where the heavy vector boson couples predominantly to fermions and to bosons, respectively. These are the most stringent limits placed on the Heavy Vector Triplet Z ' model to date. If the heavy vector boson couples exclusively to standard model bosons, upper limits on the product of the cross section and branching fraction are set between 23 and 0.3 fb for a Z ' mass between 0.8 and 4.6 Te, respectively. This is the first limit set on a heavy vector boson coupling exclusively to standard model bosons in its production and decay.Article Citation - WoS: 60Citation - Scopus: 81Measurements of Production Cross Sections of the Higgs Boson in the Four-Lepton Final State in Proton-Proton Collisions at Root S=13 Tev(Springer, 2021) Karapınar, Güler; CMS CollaborationProduction cross sections of the Higgs boson are measured in the H -> ZZ -> 4l (l = e, mu) decay channel. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS detector at the LHC and corresponding to an integrated luminosity of 137 fb(-1) is used. The signal strength modifier mu, defined as the ratio of the Higgs boson production rate in the 4l channel to the standard model (SM) expectation, is measured to be mu = 0.94 +/- 0.07 (stat)(-0.08)(+0.09) (syst) at a fixed value of m(H) = 125.38 GeV. The signal strength modifiers for the individual Higgs boson production modes are also reported. The inclusive fiducial cross section for the H -> 4l process is measured to be 2.84(-0.22)(+0.23) (stat)(-0.21)(+0.26) (syst) fb, which is compatible with the SM prediction of 2.84 +/- 0.15 fb for the same fiducial region. Differential cross sections as a function of the transverse momentum and rapidity of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet are measured. A new set of cross section measurements in mutually exclusive categories targeted to identify production mechanisms and kinematical features of the events is presented. The results are in agreement with the SM predictions.Article Citation - WoS: 35Citation - Scopus: 42Search for Charged Higgs Bosons Produced in Vector Boson Fusion Processes and Decaying Into Vector Boson Pairs in Proton-Proton Collisions at Root S=13 Tev(Springer, 2021) CMS Collaboration; Karapınar, GülerA search for charged Higgs bosons produced in vector boson fusion processes and decaying into vector bosons, using proton-proton collisions at root s = 13 TeV at the LHC, is reported. The data sample corresponds to an integrated luminosity of 137 fb(-1) collected with the CMS detector. Events are selected by requiring two or three electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass. No excess of events with respect to the standard model background predictions is observed. Model independent upper limits at 95% confidence level are reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass, from 200 to 3000 GeV. The results are interpreted in the context of the Georgi-Machacek model.Article Citation - WoS: 69Search for Higgs Boson Pair Production in the Gamma Gamma B(b)over-Bar Final State in Pp Collisions at Root S=13 Tev(Elsevier Ltd., 2019) Karapınar, Güler; CMS CollaborationA search is presented for the production of a pair of Higgs bosons, where one decays into two photons and the other one into a bottom quark-antiquark pair. The analysis is performed using proton-proton collision data at root s = 13 TeV recorded in 2016 by the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb(-1) . The results are in agreement with standard model (SM) predictions. In a search for resonant production, upper limits are set on the cross section for new spin-0 or spin-2 particles. For the SM-like nonresonant production hypothesis, the data exclude a product of cross section and branching fraction larger than 2.0 fb at 95% confidence level (CL), corresponding to about 24 times the SM prediction. Values of the effective Higgs boson self-coupling K X are constrained to be within the range -11 < K-lambda < 17 at 95% CL, assuming all other Higgs boson couplings are at their SM value. The constraints on K-lambda, are the most restrictive to date. (C) 2018 The Author(s). Published by Elsevier B.V.Article Citation - WoS: 187Citation - Scopus: 313Observation of Higgs Boson Decay To Bottom Quarks(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerThe observation of the standard model (SM) Higgs boson decay to a pair of bottom quarks is presented. The main contribution to this result is from processes in which Higgs bosons are produced in association with a W or Z boson (VH), and are searched for in final states including 0, 1, or 2 charged leptons and two identified bottom quark jets. The results from the measurement of these processes in a data sample recorded by the CMS experiment in 2017, comprising 41.3 fb-1 of proton-proton collisions at s=13 TeV, are described. When combined with previous VH measurements using data collected at s=7, 8, and 13 TeV, an excess of events is observed at mH=125 GeV with a significance of 4.8 standard deviations, where the expectation for the SM Higgs boson is 4.9. The corresponding measured signal strength is 1.01±0.22. The combination of this result with searches by the CMS experiment for H→bb in other production processes yields an observed (expected) significance of 5.6 (5.5) standard deviations and a signal strength of 1.04±0.20.Article Citation - WoS: 102Citation - Scopus: 153Search for Additional Neutral Mssm Higgs Bosons in the ? ? Final State in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search is presented for additional neutral Higgs bosons in the τ τ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into τ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks, assuming a narrow width resonance. In the mh hod + scenario these limits translate into a 95% CL exclusion of tan β > 6 for neutral Higgs boson masses below 250 GeV, where tan β is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. The 95% CL exclusion contour reaches 1.6 TeV for tan β = 60.Article Citation - WoS: 10Citation - Scopus: 33Search for Dark Matter Produced in Association With a Higgs Boson Decaying To ?? or ? + ? - at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search for dark matter particles is performed by looking for events with large transverse momentum imbalance and a recoiling Higgs boson decaying to either a pair of photons or a pair of τ leptons. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV collected at the CERN LHC in 2016 and corresponding to an integrated luminosity of 35.9 fb−1. No significant excess over the expected standard model background is observed. Upper limits at 95% confidence level are presented for the product of the production cross section and branching fraction in the context of two benchmark simplified models. For the Z′-two-Higgs-doublet model (where Z′ is a new massive boson mediator) with an intermediate heavy pseudoscalar particle of mass mA = 300 GeV and mDM = 100 GeV, the Z′ masses from 550 GeV to 1265 GeV are excluded. For a baryonic Z′ model, with mDM = 1 GeV, Z′ masses up to 615 GeV are excluded. Results are also presented for the spin-independent cross section for the dark matter-nucleon interaction as a function of the mass of the dark matter particle. This is the first search for dark matter particles produced in association with a Higgs boson decaying to two τ leptonsArticle Citation - WoS: 41Citation - Scopus: 62Search for Beyond the Standard Model Higgs Bosons Decaying Into a B B ¯ Pair in Pp Collisions at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search for Higgs bosons that decay into a bottom quark-antiquark pair and are accompanied by at least one additional bottom quark is performed with the CMS detector. The data analyzed were recorded in proton-proton collisions at a centre-of-mass energy of s=13 TeV at the LHC, corresponding to an integrated luminosity of 35.7 fb−1. The final state considered in this analysis is particularly sensitive to signatures of a Higgs sector beyond the standard model, as predicted in the generic class of two Higgs doublet models (2HDMs). No signal above the standard model background expectation is observed. Stringent upper limits on the cross section times branching fraction are set for Higgs bosons with masses up to 1300 GeV. The results are interpreted within several MSSM and 2HDM scenarios.Article Citation - WoS: 21Citation - Scopus: 64Evidence for Associated Production of a Higgs Boson With a Top Quark Pair in Final States With Electrons, Muons, and Hadronically Decaying ? Leptons at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerResults of a search for the standard model Higgs boson produced in association with a top quark pair (t t ¯ H) in final states with electrons, muons, and hadronically decaying τ leptons are presented. The analyzed data set corresponds to an integrated luminosity of 35.9 fb−1 recorded in proton-proton collisions at s=13 TeV by the CMS experiment in 2016. The sensitivity of the search is improved by using matrix element and machine learning methods to separate the signal from backgrounds. The measured signal rate amounts to 1.23− 0.43 + 0.45 times the production rate expected in the standard model, with an observed (expected) significance of 3.2σ (2.8σ), which represents evidence for t t ¯ H production in those final states. An upper limit on the signal rate of 2.1 times the standard model production rate is set at 95% confidence level.Article Citation - WoS: 50Citation - Scopus: 63Search for Resonant Pair Production of Higgs Bosons Decaying To Bottom Quark-Antiquark Pairs in Proton-Proton Collisions at 13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search for a narrow-width resonance decaying into two Higgs bosons, each decaying into a bottom quark-antiquark pair, is presented. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 35.9 fb−1 at s=13 TeV recorded by the CMS detector at the LHC. No evidence for such a signal is observed. Upper limits are set on the product of the production cross section for the resonance and the branching fraction for the selected decay mode in the resonance mass range from 260 to 1200 GeV.