Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 23Citation - Scopus: 32Search for a Heavy Higgs Boson Decaying Into Two Lighter Higgs Bosons in the Tau Tau Bb Final State at 13tev(Springer, 2021) Karapınar, Güler; CMS CollaborationA search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h(S) is presented. The h and h(S) bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137 fb(-1). Mass ranges of 240-3000 GeV for m(H) and 60-2800 GeV for m(hS) are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for m(H) = 240 GeV) to 2.7 fb (for m(H) = 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model.Article Citation - WoS: 22Citation - Scopus: 23Measurements of the Pp -> W-+/-gamma Gamma and Pp -> Z Gamma Gamma Cross Sections at Root S=13 Tev and Limits on Anomalous Quartic Gauge Couplings(Springer, 2021) Karapınar, GülerThe cross section for W or Z boson production in association with two photons is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data set corresponds to an integrated luminosity of 137 fb(-1) collected by the CMS experiment at the LHC. The W -> l nu and Z -> ll decay modes (where l = e, mu) are used to extract the W gamma gamma and Z gamma gamma cross sections in a phase space defined by electron (muon) with transverse momentum larger than 30 GeV and photon transverse momentum larger than 20 GeV. All leptons and photons are required to have absolute pseudorapidity smaller than 2.5. The measured cross sections in this phase space are sigma(W gamma gamma) = 13.6(-1.9)(+1.9) (stat)(-4.0)(+4.0) (syst) +/- 0.08 (PDF + scale) fb and sigma(Z gamma gamma) = 5.41(-0.55)(+0.58) (stat)(-0.70)(+0.64) (syst) +/- 0.06 (PDF + scale) fb. Limits on anomalous quartic gauge couplings are set in the framework of an effective field theory with dimension-8 operators.Article Citation - WoS: 16Citation - Scopus: 16Dependence of Inclusive Jet Production on the Anti-K(t) Distance Parameter in Pp Collisions at Root S=13 Tev(Springer, 2020) CMS Collaboration; Karapınar, GülerThe dependence of inclusive jet production in proton-proton collisions with a center-of-mass energy of 13 TeV on the distance parameter R of the anti-k(T) algorithm is studied using data corresponding to integrated luminosities up to 35.9 fb(-1) collected by the CMS experiment in 2016. The ratios of the inclusive cross sections as functions of transverse momentum p(T) and rapidity y, for R in the range 0.1 to 1.2 to those using R = 0.4 are presented in the region 84 < p(T)< 1588 GeV and |y|< 2.0. The results are compared to calculations at leading and next-to-leading order in the strong coupling constant using different parton shower models. The variation of the ratio of cross sections with R is well described by calculations including a parton shower model, but not by a leading-order quantum chromodynamics calculation including nonperturbative effects. The agreement between the data and the theoretical predictions for the ratios of cross sections is significantly improved when next-to-leading order calculations with nonperturbative effects are used.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: 12Citation - Scopus: 20Study of Drell-Yan Dimuon Production in Proton-Lead Collisions at Root S(nn )=8.16 Tev(Springer, 2021) Karapınar, Güler; CMS CollaborationDifferential cross sections for the Drell-Yan process, including Z boson production, using the dimuon decay channel are measured in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of 8.16 TeV. A data sample recorded with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 173 nb(-1). The differential cross section as a function of the dimuon mass is measured in the range 15-600 GeV, for the first time in proton-nucleus collisions. It is also reported as a function of dimuon rapidity over the mass ranges 15-60 GeV and 60-120 GeV, and ratios for the p-going over the Pb-going beam directions are built. In both mass ranges, the differential cross sections as functions of the dimuon transverse momentum p(T), and of a geometric variable phi* are measured, where phi* highly correlates with p(T), but is determined with higher precision. In the Z mass region, the rapidity dependence of the data indicate a modification of the distribution of partons within a lead nucleus as compared to the proton case. The data are more precise than predictions based upon current models of parton distributions.Article Citation - WoS: 20Citation - Scopus: 32Search for Dark Photons in Higgs Boson Production Via Vector Boson Fusion in Proton-Proton Collisions at Root S=13 Tev(Springer, 2021) Karapınar, Güler; CMS CollaborationA search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb(-1), recorded at a center-of-mass energy of 13 TeV in 2016-2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.Article Citation - WoS: 22Citation - Scopus: 21In-Medium Modification of Dijets in Pbpb Collisions at Root S(nn)=5.02 Tev(Springer, 2021) CMS Collaboration; Karapınar, GülerModifications to the distribution of charged particles with respect to high transverse momentum (p(T)) jets passing through a quark-gluon plasma are explored using the CMS detector. Back-to-back dijets are analyzed in lead-lead and proton-proton collisions at root s(NN) = 5.02 TeV via correlations of charged particles in bins of relative pseudorapidity and angular distance from the leading and subleading jet axes. In comparing the lead-lead and proton-proton collision results, modifications to the charged-particle relative distance distribution and to the momentum distributions around the jet axis are found to depend on the dijet momentum balance x(j) , which is the ratio between the subleading and leading jet p(T). For events with x(j) approximate to 1, these modifications are observed for both the leading and subleading jets. However, while subleading jets show significant modifications for events with a larger dijet momentum imbalance, much smaller modifications are found for the leading jets in these events.Article Citation - WoS: 70Citation - Scopus: 59First Measurement of Large Area Jet Transverse Momentum Spectra in Heavy-Ion Collisions(Springer Science and Business Media Deutschland GmbH, 2021) Karapınar, Güler; CMS CollaborationJet production in lead-lead (PbPb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is studied with the CMS detector at the LHC, using PbPb and pp data samples corresponding to integrated luminosities of 404 ?b?1 and 27.4 pb?1, respectively. Jets with different areas are reconstructed using the anti-kT algorithm by varying the distance parameter R. The measurements are performed using jets with transverse momenta (pT) greater than 200 GeV and in a pseudorapidity range of |?| < 2. To reveal the medium modification of the jet spectra in PbPb collisions, the properly normalized ratio of spectra from PbPb and pp data is used to extract jet nuclear modification factors as functions of the PbPb collision centrality, pT and, for the first time, as a function of R up to 1.0. For the most central collisions, a strong suppression is observed for high-pT jets reconstructed with all distance parameters, implying that a significant amount of jet energy is scattered to large angles. The dependence of jet suppression on R is expected to be sensitive to both the jet energy loss mechanism and the medium response, and so the data are compared to several modern event generators and analytic calculations. The models considered do not fully reproduce the data. [Figure not available: see fulltext.] © 2021, The Author(s).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: 14Citation - Scopus: 14The Production of Isolated Photons in Pbpb and Pp Collisions at Root S(nn)=5.02 Tev(Springer Verlag, 2020) Karapınar, GülerThe transverse energy (ET gamma) spectra of photons isolated from other particles are measured using proton-proton (pp) and lead-lead (PbPb) collisions at the LHC at root s(NN) = 5.02 TeV with integrated luminosities of 27.4 pb(-1) and 404 mu b(-1) for pp and PbPb data, respectively. The results are presented for photons with 25 < E-T(gamma)< 200 GeV in the pseudorapidity range vertical bar eta vertical bar < 1.44, and for different centrality intervals for PbPb collisions. Photon production in PbPb collisions is consistent with that in pp collisions scaled by the number of binary nucleon-nucleon collisions, demonstrating that photons do not interact with the quark-gluon plasma. Therefore, isolated photons can provide information about the initial energy of the associated parton in photon+jet measurements. The results are compared with predictions from the next-to-leading-order jetphox generator for different parton distribution functions (PDFs) and nuclear PDFs (nPDFs). The comparisons can help to constrain the nPDFs global fits.