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Permanent URI for this collectionhttps://hdl.handle.net/11147/6849
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Article Citation - WoS: 33Search for Physics Beyond the Standard Model Using Multilepton Signatures in Pp Collisions at Root S=7 Tev(Elsevier Ltd., 2011) Demir, Durmuş Ali; Karapınar, Güler; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA search for physics beyond the standard model in events with at least three leptons and any number of jets is presented. The data sample corresponds to 35 pb(-1) of integrated luminosity in pp collisions at root s = 7 TeV collected by the CMS experiment at the LHC. A number of exclusive multileptonic channels are investigated and standard model backgrounds are suppressed by requiring sufficient missing transverse energy, invariant mass inconsistent with that of the Z boson, or high jet activity. Control samples in data are used to ascertain the robustness of background evaluation techniques and to minimise the reliance on simulation. The observations are consistent with background expectations. These results constrain previously unexplored regions of supersymmetric parameter space. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.Article Citation - WoS: 180Citation - Scopus: 112Search for Neutral Mssm Higgs Bosons Decaying To a Pair of Tau Leptons in Pp Collisions(Springer Verlag, 2014) Karapınar, Güler; Karapınar, Güler; Demir, Durmuş Ali; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA search for neutral Higgs bosons in the minimal supersymmetric extension of the standard model (MSSM) decaying to tau-lepton pairs in pp collisions is performed, using events recorded by the CMS experiment at the LHC. The dataset corresponds to an integrated luminosity of 24.6 fb(-1), with 4.9 fb(-1) at 7TeV and 19.7 fb(-1) at 8TeV. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes the case where the Higgs boson is produced in association with a b-quark jet. No excess is observed in the tau-lepton-pair invariant mass spectrum. Exclusion limits are presented in the MSSM parameter space for different benchmark scenarios, m(h)(max), m(h)(mod+), m(h)(mod-), light-stop, light-stau, T-phobic, and low-m(H). Upper limits on the cross section times branching fraction for gluon fusion and b-quark associated Higgs boson production are also given.Article Citation - WoS: 80Citation - Scopus: 68Search for Disappearing Tracks in Proton-Proton Collisions at Root S=8 Tev(Springer Verlag, 2015) Karapınar, Güler; Demir, Durmuş Ali; Demir, Durmuş Ali; Karapınar, Güler; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA search is presented for long-lived charged particles that decay within the CMS detector and produce the signature of a disappearing track. Disappearing tracks are identified as those with little or no associated calorimeter energy deposits and with missing hits in the outer layers of the tracker. The search uses proton-proton collision data recorded at root s = 8 TeV that corresponds to an integrated luminosity of 19.5 fb(-1). The results of the search are interpreted in the context of the anomaly-mediated supersymmetry breaking (AMSB) model. The number of observed events is in agreement with the background expectation, and limits are set on the cross section of direct electroweak chargino production in terms of the chargino mass and mean proper lifetime. At 95% confidence level, AMSB models with a chargino mass less than 260 GeV, corresponding to a mean proper lifetime of 0.2 ns, are excluded.Article Citation - WoS: 8Citation - Scopus: 15Search for Supersymmetry in Proton-Proton Collisions at <mml:msqrt>s</Mml:msqrt>=13 Tev in Events With High-Momentum Z Bosons and Missing Transverse Momentum(Springer Verlag, 2020) Karapınar, Güler; Karapınar, Güler; Demir, Durmuş Ali; Demir, Durmuş Ali; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA search for new physics in events with two highly Lorentz-boosted Z bosons and large missing transverse momentum is presented. The analyzed proton-proton collision data, corresponding to an integrated luminosity of 137 fb(-1), were recorded at s = 13 TeV by the CMS experiment at the CERN LHC. The search utilizes the substructure of jets with large radius to identify quark pairs from Z boson decays. Backgrounds from standard model processes are suppressed by requirements on the jet mass and the missing transverse momentum. No significant excess in the event yield is observed beyond the number of background events expected from the standard model. For a simplified supersymmetric model in which the Z bosons arise from the decay of gluinos, an exclusion limit of 1920 GeV on the gluino mass is set at 95% confidence level. This is the first search for beyond-standard-model production of pairs of boosted Z bosons plus large missing transverse momentum.Article Citation - WoS: 44Citation - Scopus: 48Search for Supersymmetry in Pp Collisions at ?s=7tev in Events With Two Photons and Missing Transverse Energy(American Physical Society, 2011) Karapınar, Güler; Demir, Durmuş Ali; Karapınar, Güler; 04.05. Department of Pyhsics; 01. Izmir Institute of Technology; 04. Faculty of ScienceA search for supersymmetry in the context of general gauge-mediated breaking with the lightest neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest is presented. The data sample corresponds to an integrated luminosity of 36pb-1 recorded by the CMS experiment at the LHC. The search is performed by using events containing two or more isolated photons, at least one hadronic jet, and significant missing transverse energy. No excess of events at high missing transverse energy is observed. Upper limits on the signal cross section for general gauge-mediated supersymmetry between 0.3 and 1.1 pb at the 95% confidence level are determined for a range of squark, gluino, and neutralino masses, excluding supersymmetry parameter space that was inaccessible to previous experiments. © 2011 American Physical Society.