Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
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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: 17Search for Pair Production of Excited Top Quarks in the Lepton + Jets Final State(Elsevier, 2018) CMS Collaboration; Karapınar, GülerA search is performed for the pair production of spin-3/2 excited top quarks, each decaying to a top quark and a gluon. The search uses the data collected with the CMS detector from proton–proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Events are selected by requiring an isolated muon or electron, an imbalance in the transverse momentum, and at least six jets of which exactly two must be compatible with originating from the fragmentation of a bottom quark. No significant excess over the standard model predictions is found. A lower limit of 1.2 TeV is set at 95% confidence level on the mass of the spin-3/2 excited top quark in an extension of the Randall–Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. These are the best limits to date in a search for excited top quarks and the first at 13 TeV.Article Citation - WoS: 34Citation - Scopus: 35Search for quark contact interactions and extra spatial dimensions using dijet angular distributions in proton–proton collisions at S=8 TeV(Elsevier, 2015) CMS Collaboration; Karapınar, GülerA search is presented for quark contact interactions and extra spatial dimensions in proton–proton collisions at s=8 TeV using dijet angular distributions. The search is based on a data set corresponding to an integrated luminosity of 19.7 fb−1 collected by the CMS detector at the CERN LHC. Dijet angular distributions are found to be in agreement with the perturbative QCD predictions that include electroweak corrections. Limits on the contact interaction scale from a variety of models at next-to-leading order in QCD corrections are obtained. A benchmark model in which only left-handed quarks participate is excluded up to a scale of 9.0 (11.7) TeV for destructive (constructive) interference at 95% confidence level. Lower limits between 5.9 and 8.4 TeV on the scale of virtual graviton exchange are extracted for the Arkani-Hamed–Dimopoulos–Dvali model of extra spatial dimensions. © 2015 CERN for the benefit of the CMS CollaborationArticle Citation - WoS: 26Citation - Scopus: 22Searches for supersymmetry based on events with B jets and four W bosons in Pp collisions at 8 Tev(Elsevier, 2015) CMS Collaboration; Karapınar, GülerFive mutually exclusive searches for supersymmetry are presented based on events in which b jets and four W bosons are produced in proton–proton collisions at s=8 TeV. The data, corresponding to an integrated luminosity of 19.5 fb−1, were collected with the CMS experiment at the CERN LHC in 2012. The five studies differ in the leptonic signature from the W boson decays, and correspond to all-hadronic, single-lepton, opposite-sign dilepton, same-sign dilepton, and ≥3 lepton final states. The results of the five studies are combined to yield 95% confidence level limits for the gluino and bottom-squark masses in the context of gluino and bottom-squark pair production, respectively. In the limit when the lightest supersymmetric particle is light, gluino and bottom squark masses are excluded below 1280 and 570 GeV, respectively. © 2015 CERN for the benefit of the CMS CollaborationArticle Citation - WoS: 77Citation - Scopus: 79Search for pair-produced resonances decaying to jet pairs in proton–proton collisions at S=8 TeV(Elsevier, 2015) CMS Collaboration; Karapınar, GülerResults are reported of a general search for pair production of heavy resonances decaying to pairs of hadronic jets in events with at least four jets. The study is based on up to 19.4 fb−1 of integrated luminosity from proton–proton collisions at a center-of-mass energy of 8 TeV, recorded with the CMS detector at the LHC. Limits are determined on the production of scalar top quarks (top squarks) in the framework of R-parity violating supersymmetry and on the production of color-octet vector bosons (colorons). First limits at the LHC are placed on top squark production for two scenarios. The first assumes decay to a bottom quark and a light-flavor quark and is excluded for masses between 200 and 385 GeV, and the second assumes decay to a pair of light-flavor quarks and is excluded for masses between 200 and 350 GeV at 95% confidence level. Previous limits on colorons decaying to light-flavor quarks are extended to exclude masses from 200 to 835 GeV. © 2015 CERN for the benefit of the CMS Collaboration