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: 4Citation - Scopus: 8Search for the Rare Decay of the W Boson Into a Pion and a Photon in Proton-Proton Collisions at S=13tev(Elsevier B.V., 2021) Sirunyan,A.M.; Karapınar, Güler; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Chistov,R.A search is performed for the rare decay W±→π±γ in proton-proton collisions at s=13TeV. Data corresponding to an integrated luminosity of 137fb−1 were collected during 2016 to 2018 with the CMS detector. This analysis exploits a novel search strategy based on W boson production in top quark pair events. An inclusive search for the W±→π±γ decay is not optimal at the LHC because of the high trigger thresholds. Instead, a trigger selection is exploited in which the W boson originating from one of the top quarks is used to tag the event in a leptonic decay. The W boson emerging from the other top quark is used to search for the W±→π±γ signature. Such decays are characterized by an isolated track pointing to a large energy deposit, and by an isolated photon of large transverse momentum. The presence of b quark jets reduces the background from the hadronization of light-flavor quarks and gluons. The W±→π±γ decay is not observed. An upper exclusion limit is set to this branching fraction, corresponding to 1.50×10−5 at 95% confidence level, whereas the expected upper exclusion limit is 0.85−0.29 +0.52×10−5. © 2021 The Author(s)Article Citation - WoS: 40Citation - Scopus: 46Measurement of the Associated Production of a Single Top Quark and a Z Boson in Pp Collisions At, Root S=13 Tev(Elsevier Ltd., 2018) Karapınar, Güler; CMS CollaborationA measurement is presented of the associated production of a single top quark and a Z boson. The study uses data from proton-proton collisions at, root s = 13 TeV recorded by the CMS experiment, corresponding to an integrated luminosity of 35.9 fb(-1). Using final states with three leptons (electrons or muons), the tZq production cross section is measured to be sigma (pp -> tZq -> Wbl(+)l(-)q) = 123(-31)(+33)(stat)(-23)(+29)(syst) fb, where l stands for electrons, muons, or tau leptons, with observed and expected significances of 3.7 and 3.1 standard deviations, respectively. C) 2018 The Author. Published by Elsevier B.V.Article Citation - WoS: 30Citation - Scopus: 30Search for a Heavy Resonance Decaying Into a Z Boson and a Vector Boson in the ??¯qq¯ Final State(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search is presented for a heavy resonance decaying into either a pair of Z bosons or a Z boson and a W boson (ZZ or WZ), with a Z boson decaying into a pair of neutrinos and the other boson decaying hadronically into two collimated quarks that are reconstructed as a highly energetic large-cone jet. The search is performed using the data collected with the CMS detector at the CERN LHC during 2016 in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 35.9 fb−1. No excess is observed in data with regard to background expectations. Results are interpreted in scenarios of physics beyond the standard model. Limits at 95% confidence level on production cross sections are set at 0.9 fb (63 fb) for spin-1 W′ bosons, included in the heavy vector triplet model, with mass 4.0 TeV (1.0 TeV), and at 0.5 fb (40 fb) for spin-2 bulk gravitons with mass 4.0 TeV (1.0 TeV). Lower limits are set on the masses of W′ bosons in the context of two versions of the heavy vector triplet model of 3.1TeV and 3.4 TeV, respectively.Article Citation - WoS: 11Citation - Scopus: 23Search for Physics Beyond the Standard Model in Events With High-Momentum Higgs Bosons and Missing Transverse Momentum in Proton-Proton Collisions at 13 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerA search for physics beyond the standard model in events with one or more high-momentum Higgs bosons, H, decaying to pairs of b quarks in association with missing transverse momentum is presented. The data, corresponding to an integrated luminosity of 35.9 fb-1, were collected with the CMS detector at the LHC in proton-proton collisions at the center-of-mass energy s=13 TeV. The analysis utilizes a new b quark tagging technique based on jet substructure to identify jets from H→bb. Events are categorized by the multiplicity of H-tagged jets, jet mass, and the missing transverse momentum. No significant deviation from standard model expectations is observed. In the context of supersymmetry (SUSY), limits on the cross sections of pair-produced gluinos are set, assuming that gluinos decay to quark pairs, H (or Z), and the lightest SUSY particle, LSP, through an intermediate next-to-lightest SUSY particle, NLSP. With large mass splitting between the NLSP and LSP, and 100% NLSP branching fraction to H, the lower limit on the gluino mass is found to be 2010 GeV.Article Citation - WoS: 92Citation - Scopus: 211Search for Heavy Neutral Leptons in Events With Three Charged Leptons in Proton-Proton Collisions at ?s = 13 Tev(American Physical Society, 2018) CMS Collaboration; Karapınar, GülerA search for a heavy neutral lepton N of Majorana nature decaying into a W boson and a charged lepton is performed using the CMS detector at the LHC. The targeted signature consists of three prompt charged leptons in any flavor combination of electrons and muons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV, with an integrated luminosity of 35.9 fb-1. The search is performed in the N mass range between 1 GeV and 1.2 TeV. The data are found to be consistent with the expected standard model background. Upper limits are set on the values of |VeN|2 and |VμN|2, where V N is the matrix element describing the mixing of N with the standard model neutrino of flavor. These are the first direct limits for N masses above 500 GeV and the first limits obtained at a hadron collider for N masses below 40 GeV.Article Citation - WoS: 82Citation - Scopus: 100Evidence for the Higgs Boson Decay To a Bottom Quark–antiquark Pair(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerA search for the standard model (SM) Higgs boson (H) decaying to bb‾ when produced in association with an electroweak vector boson is reported for the following processes: Z(νν)H, W(μν)H, W(eν)H, Z(μμ)H, and Z(ee)H. The search is performed in data samples corresponding to an integrated luminosity of 35.9fb−1 at s=13TeV recorded by the CMS experiment at the LHC during Run 2 in 2016. An excess of events is observed in data compared to the expectation in the absence of a H→bb‾ signal. The significance of this excess is 3.3 standard deviations, where the expectation from SM Higgs boson production is 2.8. The signal strength corresponding to this excess, relative to that of the SM Higgs boson production, is 1.2±0.4. When combined with the Run 1 measurement of the same processes, the signal significance is 3.8 standard deviations with 3.8 expected. The corresponding signal strength, relative to that of the SM Higgs boson, is 1.06−0.29 +0.31.Article Citation - WoS: 29Citation - Scopus: 55Search for a Heavy Right-Handed W Boson and a Heavy Neutrino in Events With Two Same-Flavor Leptons and Two Jets at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search for a heavy right-handed W boson (WR) decaying to a heavy right-handed neutrino and a charged lepton in events with two same-flavor leptons (e or μ) and two jets, is presented. The analysis is based on proton-proton collision data, collected by the CMS Collaboration at the LHC in 2016 and corresponding to an integrated luminosity of 35.9 fb−1. No significant excess above the standard model expectation is seen in the invariant mass distribution of the dilepton plus dijet system. Assuming that couplings are identical to those of the standard model, and that only one heavy neutrino flavor NR contributes significantly to the WR decay width, the region in the two-dimensional (mWRmNR) mass plane excluded at 95% confidence level extends to approximately mWR=4.4 TeV and covers a large range of right-handed neutrino masses below the WR boson mass. This analysis provides the most stringent limits on the WR mass to date.Article Citation - WoS: 4Citation - Scopus: 4Hidden Spin-3/2 Field in the Standard Model(Springer Verlag, 2017) Demir, Durmuş Ali; Karahan, Canan; Korutlu, Beste; Sargın, OzanHere we show that a massive spin-3/2 field can hide in the SM spectrum in a way revealing itself only virtually. We study collider signatures and loop effects of this field, and determine its role in Higgs inflation and its potential as dark matter. We show that this spin-3/2 field has a rich linear collider phenomenology and motivates consideration of a neutrino–Higgs collider. We also show that the study of Higgs inflation, dark matter and dark energy can reveal more about the neutrino and dark sector. © 2017, The Author(s).Article Citation - WoS: 2Citation - Scopus: 2Higgsed Stueckelberg Vector and Higgs Quadratic Divergence(Elsevier Ltd., 2015) Demir, Durmuş Ali; Karahan, Canan Nurhan; Korutlu, BesteHere we show that, a hidden vector field whose gauge invariance is ensured by a Stueckelberg scalar and whose mass is spontaneously generated by the Standard Model Higgs field contributes to quadratic divergences in the Higgs boson mass squared, and even leads to its cancellation at one-loop when Higgs coupling to gauge field is fine-tuned. In contrast to mechanisms based on hidden scalars where a complete cancellation cannot be achieved, stabilization here is complete in that the hidden vector and the accompanying Stueckelberg scalar are both free from quadratic divergences at one-loop. This stability, deriving from hidden exact gauge invariance, can have important implications for modeling dark phenomena like dark matter, dark energy, dark photon and neutrino masses. The hidden fields can be produced at the LHC.Article Citation - WoS: 23Citation - Scopus: 26Curvature-Restored Gauge Invariance and Ultraviolet Naturalness(Hindawi Publishing Corporation, 2016) Demir, Durmuş AliIt is shown that (aΛ2+b|H|2)R in a spacetime of curvature R is a natural ultraviolet (UV) completion of (aΛ4+bΛ2|H|2) in the flat-spacetime Standard Model (SM) with Higgs field H, UV scale Λ, and loop factors a and b. This curvature completion rests on the fact that Λ-mass gauge theory in flat spacetime turns, on the cut view R=4Λ2, into a massless gauge theory in curved spacetime. It provides a symmetry reason for curved spacetime, wherein gravity and matter are both low-energy effective phenomena. Gravity arises correctly if new physics exists with at least 63 more bosons than fermions, with no need to interact with the SM and with dark matter as a natural harbinger. It can source various cosmological, astrophysical, and collider phenomena depending on its spectrum and couplings to the SM.