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: 1Citation - Scopus: 1Type-3/2 Seesaw Mechanism(American Physical Society, 2021) Demir, Durmuş Ali; Karahan, Canan; Sargın, OzanThe type-I seesaw mechanism provides a natural explanation for tiny neutrino masses. The right-handed neutrino masses it requires are, however, too large to keep the Higgs boson mass at its measured value. We show that vector spinors, singlet leptons that are like right-handed neutrinos, generate tiny neutrino masses naturally through the exchange of spin-1/2 and spin-3/2 components. This one-step seesaw mechanism, which we call the type-3/2 seesaw, keeps the Higgs boson mass unchanged at one loop and gives cause therefore to no fine-tuning problem. If the on-shell vector spinor is a pure spin-3/2 particle, then it becomes a potential candidate for hidden dark matter which gets diluted due only to the expansion of the Universe. The type-3/2 seesaw provides a natural framework for the neutrino, Higgs boson, and dark matter sectors, with overall agreement with current experiments and observations.Article Citation - WoS: 26Citation - Scopus: 54Search for Heavy Stable Charged Particles in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe result of a search at the LHC for heavy stable charged particles produced in pp collisions at root s = 7TeV is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb(-1). Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398 GeV/c(2), using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c(2) is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.Article Citation - WoS: 153Citation - Scopus: 137Strange Particle Production in Pp Collisions at Root S=0.9 and 7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7TeV. The K-S(0), A, and Xi(-) particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum, p(T). The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The p(T) distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.Article Citation - WoS: 18Citation - Scopus: 29Search for Large Extra Dimensions in the Diphoton Final State at the Large Hadron Collider(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA search for large extra spatial dimensions via virtual-graviton exchange in the diphoton channel has been carried out with the CMS detector at the LHC. No excess of events above the standard model expectations is found using a data sample collected in proton-proton collisions at root s = 7TeV and corresponding to an integrated luminosity of 36 pb(-1). New lower limits on the effective Planck scale in the range of 1.6-2.3TeV at the 95% confidence level are set, providing the most restrictive bounds to date on models with more than two large extra dimensions.Article Citation - WoS: 30Citation - Scopus: 37Search for Supersymmetry in Events With B Jets and Missing Transverse Momentum at the Lhc(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliA search for supersymmetry is presented using a sample of events with b jets and missing transverse momentum. The search uses a data sample of proton-proton collisions at a centre-of-mass energy of 7TeV, corresponding to an integrated luminosity of 35 pb(-1), collected with the CMS detector. A total of 0.33(-0.33)(+0.43) (stat.) +/- 0.13 (syst.) events is predicted, using control samples in the data, to arise from standard model processes, and one event is observed in the data. Upper limits are set at the 95% confidence level on the cross sections of benchmark supersymmetric models.Article Citation - WoS: 25Citation - Scopus: 87Measurement of the T(t)over-Bar Production Cross Section and the Top Quark Mass in the Dilepton Channel in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe t (t) over bar production cross section and top quark mass are measured in proton-proton collisions at root s = 7 TeV in a data sample corresponding to an integrated luminosity of 36 pb(-1) collected by the CMS experiment. The measurements are performed in events with two leptons (electrons or muons) in the final state. Results of the cross section measurement in events with and without b-quark identification are obtained and combined. The measured value is sigma(tt) - 168 +/- 18 (stat:) +/- 14 (syst:) +/- 7 (lumi:) pb, consistent with predictions from the standard model. The top quark mass m(top) is reconstructed with two different methods, a full kinematic analysis and a matrix weighting technique. The combination yields a measurement of m(top) = 175.5 +/- 4.6 (stat:) +/- 4: 6 (syst:) GeV/c(2).Article Citation - WoS: 42Citation - Scopus: 38Measurement of the Inclusive Z Cross Section Via Decays To Tau Pairs in Pp Collisions at Root S=7 Tev(Springer Verlag, 2011) Karapınar, Güler; Demir, Durmuş AliThe first measurement of inclusive Z > tau(+) tau(-) production in pp collisions at the LHC is presented, in the final states mu+hadrons, e+hadrons, e-mu, and mu+mu. The data sample corresponds to an integrated luminosity of 36 pb(-1) collected with the CMS detector. The measured cross section is sigma (pp -> ZX) x B (Z -> tau(+)tau(-)) = 1.00 +/- 0.05 (stat.)+/- 0.08 (syst.) +/- 0.04 (lumi.) nb, which is in good agreement with the next-to-next-to-leading order QCD prediction and improves on previous measurements in the Z -> e(+)e(-) and mu(+)mu(-) channels. The reconstruction efficiency for hadronic T decays is determined with a precision of 7%.Article Citation - WoS: 63Citation - Scopus: 73Angular Analysis and Branching Fraction Measurement of the Decay B-0 -> K*(0)mu(+)mu(-)(Elsevier, 2013) Demir, Durmuş Ali; Karapınar, GülerThe angular distributions and the differential branching fraction of the decay B-0 -> K*(892)(0)mu(+)mu(-) are studied using a data sample corresponding to an integrated luminosity of 5.2 fb(-1) collected with the CMS detector at the LHC in pp collisions at root s = 7 TeV. From more than 400 signal decays, the forward-backward asymmetry of the muons, the K*(892)(0) longitudinal polarization fraction, and the differential branching fraction are determined as a function of the square of the dimuon invariant mass. The measurements are in good agreement with standard model predictions. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved.Article Citation - WoS: 31Citation - Scopus: 58Measurement of the Tt̄ production cross section in the dilepton channel in Pp collisions at √s = 8 Tev(Springer Verlag, 2014) CMS Collaboration; Demir, Durmuş AliThe top-antitop quark (tt̄) production cross section is measured in proton-proton collisions at √s = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb -1. The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The measured cross section is 239 ± 2 (stat.) ± 11 (syst.) ± 6 (lum.) pb, for an assumed top-quark mass of 172.5 GeV, in agreement with the prediction of the standard model.Article Citation - WoS: 59Citation - Scopus: 79Measurement of Associated W Plus Charm Production in Pp Collisions at Root S=7 Tev(Springer Verlag, 2014) Karapınar, Güler; Demir, Durmuş AliMeasurements are presented of the associated production of a W boson and a charm-quark jet (W + c) in pp collisions at a center-of-mass energy of 7 TeV. The analysis is conducted with a data sample corresponding to a total integrated luminosity of 5 fb(-1), collected by the CMS detector at the LHC. W boson candidates are identified by their decay into a charged lepton (muon or electron) and a neutrino. The W + c measurements are performed for charm-quark jets in the kinematic region p(T)(jet) > 25 GeV, vertical bar eta(jet)vertical bar < 2.5, for two different thresholds for the transverse momentum of the lepton from the W-boson decay, and in the pseudorapidity range eta(l) < 2.1. Hadronic and inclusive semileptonic decays of charm hadrons are used to measure the following total cross sections: sigma(pp -> W + c + X) x B (W -> lv) = 107.7 +/- 3.3 (stat.) +/- 6.9 (syst.) pb (p(T)(l) > 25 GeV) and sigma (pp -> W + c + X) x B (W -> lv) = 84.1 +/- 2.0 (stat.) +/- 4.9 (syst.) pb (p(T)(l) > 35 GeV), and the cross section ratios sigma(pp -> W+ + (c) over bar + X)/sigma(pp -> W- + c + X) = 0.954 +/- 0.025 (stat.) +/- 0.004 (syst.) (p(T)(l) > 25 GeV) and sigma(pp -> W+ + (c) over bar + X)/sigma(pp -> W- + c + X) = 0.938 +/- 0.019 (stat.) +/- 0.006 (syst.) (p(T)(l) > 35 GeV). Cross sections and cross section ratios are also measured differentially with respect to the absolute value of the pseudorapidity of the lepton from the W-boson decay. These are the first measurements from the LHC directly sensitive to the strange quark and antiquark content of the proton. Results are compared with theoretical predictions and are consistent with the predictions based on global fits of parton distribution functions.