Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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Article Citation - WoS: 52Citation - Scopus: 56Study of Jet Quenching With Isolated-Photon+jet Correlations in Pbpb and Pp Collisions at Snn=5.02 Tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerMeasurements of azimuthal angle and transverse momentum (pT) correlations of isolated photons and associated jets are reported for pp and PbPb collisions at sNN=5.02 TeV. The data were recorded with the CMS detector at the CERN LHC. For events containing a leading isolated photon with pT γ>40 GeV/c and an associated jet with pT jet>30 GeV/c, the photon+jet azimuthal correlation and pT imbalance in PbPb collisions are studied as functions of collision centrality and pT γ. The results are compared to pp reference data collected at the same collision energy and to predictions from several theoretical models for parton energy loss. No evidence of broadening of the photon+jet azimuthal correlations is observed, while the ratio pT jet/pT γ decreases significantly for PbPb data relative to the pp reference. All models considered agree within uncertainties with the data. The number of associated jets per photon with pT γ>80 GeV/c is observed to be shifted towards lower pT jet values in central PbPb collisions compared to pp collisions.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: 19Citation - Scopus: 39Search for a Singly Produced Third-Generation Scalar Leptoquark Decaying To a ? Lepton and a Bottom Quark in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search is presented for a singly produced third-generation scalar leptoquark decaying to a τ lepton and a bottom quark. Associated production of a leptoquark and a τ lepton is considered, leading to a final state with a bottom quark and two τ leptons. The search uses proton-proton collision data at a center-of-mass energy of 13 TeV recorded with the CMS detector, corresponding to an integrated luminosity of 35.9 fb−1. Upper limits are set at 95% confidence level on the production cross section of the third-generation scalar leptoquarks as a function of their mass. From a comparison of the results with the theoretical predictions, a third-generation scalar leptoquark decaying to a τ lepton and a bottom quark, assuming unit Yukawa coupling (λ), is excluded for masses below 740 GeV. Limits are also set on λ of the hypothesized leptoquark as a function of its mass. Above λ = 1.4, this result provides the best upper limit on the mass of a third-generation scalar leptoquark decaying to a τ lepton and a bottom quark.Article Citation - WoS: 152Citation - Scopus: 191Measurement of the Inelastic Proton-Proton Cross Section at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA measurement of the inelastic proton-proton cross section with the CMS detector at a center-of-mass energy of s=13 TeV is presented. The analysis is based on events with energy deposits in the forward calorimeters, which cover pseudorapidities of −6.6 < η < −3.0 and +3.0 < η < +5.2. An inelastic cross section of 68.6 ± 0.5(syst) ± 1.6(lumi) mb is obtained for events with MX> 4.1 GeV and/or MY> 13 GeV, where MX and MY are the masses of the diffractive dissociation systems at negative and positive pseudorapidities, respectively. The results are compared with those from other experiments as well as to predictions from high-energy hadron-hadron interaction models.Article Citation - WoS: 63Citation - Scopus: 76Search for Single Production of a Vector-Like T Quark Decaying To a Z Boson and a Top Quark in Proton–proton Collisions at S=13tev(Elsevier, 2018) CMS Collaboration; Karapınar, GülerA search is presented for single production of a vector-like quark (T) decaying to a Z boson and a top quark, with the Z boson decaying leptonically and the top quark decaying hadronically. The search uses data collected by the CMS experiment in proton–proton collisions at a center-of-mass energy of 13 TeV in 2016, corresponding to an integrated luminosity of 35.9fb−1. The presence of forward jets is a particular characteristic of single production of vector-like quarks that is used in the analysis. For the first time, different T quark width hypotheses are studied, from negligibly small to 30% of the new particle mass. At the 95% confidence level, the product of cross section and branching fraction is excluded above values in the range 0.26–0.04 pb for T quark masses in the range 0.7–1.7 TeV, assuming a negligible width. A similar sensitivity is observed for widths of up to 30% of the T quark mass. The production of a heavy Z′ boson decaying to Tt, with T→tZ, is also searched for, and limits on the product of cross section and branching fractions for this process are set between 0.13 and 0.06 pb for Z′ boson masses in the range from 1.5 to 2.5 TeV.Article Citation - WoS: 11Citation - Scopus: 11Search for Excited Quarks of Light and Heavy Flavor in ? +jet Final States in Proton–proton Collisions at S=13tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerA search is presented for excited quarks of light and heavy flavor that decay to γ+jet final states. The analysis is based on data corresponding to an integrated luminosity of 35.9fb−1 collected by the CMS experiment in proton–proton collisions at s=13TeV at the LHC. A signal would appear as a resonant contribution to the invariant mass spectrum of the γ+jet system, above the background expected from standard model processes. No resonant excess is found, and upper limits are set on the product of the excited quark cross section and its branching fraction as a function of its mass. These are the most stringent limits to date in the γ+jet final state, and exclude excited light quarks with masses below 5.5 TeV and excited b quarks with masses below 1.8 TeV, assuming standard model like coupling strengths.Article Citation - WoS: 47Citation - Scopus: 70Search for the X (5568) State Decaying Into B-s(0)pi(+/-) in Proton-Proton Collisions at Root S=8 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerA search for resonancelike structures in the Bs0π± invariant mass spectrum is performed using proton-proton collision data collected by the CMS experiment at the LHC at s=8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The Bs0 mesons are reconstructed in the decay chain Bs0→J/ψφ, with J/ψ→μ+μ- and φ→K+K-. The Bs0π± invariant mass distribution shows no statistically significant peaks for different selection requirements on the reconstructed Bs0 and π± candidates. Upper limits are set on the relative production rates of the X(5568) and Bs0 states times the branching fraction of the decay X(5568)±→Bs0π±. In addition, upper limits are obtained as a function of the mass and the natural width of possible exotic states decaying into Bs0π±.Article Citation - WoS: 54Citation - Scopus: 93Inclusive Search for a Highly Boosted Higgs Boson Decaying To a Bottom Quark-Antiquark Pair(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerAn inclusive search for the standard model Higgs boson (H) produced with large transverse momentum (pT) and decaying to a bottom quark-antiquark pair (bb) is performed using a data set of pp collisions at s=13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb-1. A highly Lorentz-boosted Higgs boson decaying to bb is reconstructed as a single, large radius jet, and it is identified using jet substructure and dedicated b tagging techniques. The method is validated with Z→bb decays. The Z→bb process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of H→bb with reconstructed pT>450 GeV and in the pseudorapidity range -2.5<η<2.5 is 74±48(stat)-10+17(syst) fb, which is consistent within uncertainties with the standard model prediction. © 2018 CERN.Article Citation - WoS: 30Citation - Scopus: 56Observation of Top Quark Production in Proton-Nucleus Collisions(American Physical Society, 2017) CMS Collaboration; Karapınar, GülerThe first observation of top quark production in proton-nucleus collisions is reported using proton-lead data collected by the CMS experiment at the CERN LHC at a nucleon-nucleon center-of-mass energy of sNN=8.16 TeV. The measurement is performed using events with exactly one isolated electron or muon candidate and at least four jets. The data sample corresponds to an integrated luminosity of 174 nb-1. The significance of the tt signal against the background-only hypothesis is above 5 standard deviations. The measured cross section is σtt=45±8 nb, consistent with predictions from perturbative quantum chromodynamics.Article Citation - WoS: 22Citation - Scopus: 44Search for Evidence of the Type-Iii Seesaw Mechanism in Multilepton Final States in Proton-Proton Collisions at ?s =13 Tev(American Physical Society, 2017) CMS Collaboration; Karapınar, GülerA search for a signal consistent with the type-III seesaw mechanism in events with three or more electrons or muons is presented. The data sample consists of proton-proton collisions at s=13 TeV collected by the CMS experiment at the LHC in 2016 and corresponds to an integrated luminosity of 35.9 fb-1. Selection criteria based on the number of leptons and the invariant mass of oppositely charged lepton pairs are used to distinguish the signal from the standard model background. The observations are consistent with the expectations from standard model processes. The results are used to place limits on the production of heavy fermions of the type-III seesaw model as a function of the branching ratio to each lepton flavor. In the scenario of equal branching fractions to each lepton flavor, heavy fermions with masses below 840 GeV are excluded. This is the most sensitive probe to date of the type-III seesaw mechanism.