Mathematics / Matematik
Permanent URI for this collectionhttps://hdl.handle.net/11147/8
Browse
20 results
Search Results
Article Citation - WoS: 10Citation - Scopus: 33Search for Dark Matter Produced in Association With a Higgs Boson Decaying To ?? or ? + ? - at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search for dark matter particles is performed by looking for events with large transverse momentum imbalance and a recoiling Higgs boson decaying to either a pair of photons or a pair of τ leptons. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV collected at the CERN LHC in 2016 and corresponding to an integrated luminosity of 35.9 fb−1. No significant excess over the expected standard model background is observed. Upper limits at 95% confidence level are presented for the product of the production cross section and branching fraction in the context of two benchmark simplified models. For the Z′-two-Higgs-doublet model (where Z′ is a new massive boson mediator) with an intermediate heavy pseudoscalar particle of mass mA = 300 GeV and mDM = 100 GeV, the Z′ masses from 550 GeV to 1265 GeV are excluded. For a baryonic Z′ model, with mDM = 1 GeV, Z′ masses up to 615 GeV are excluded. Results are also presented for the spin-independent cross section for the dark matter-nucleon interaction as a function of the mass of the dark matter particle. This is the first search for dark matter particles produced in association with a Higgs boson decaying to two τ leptonsArticle Citation - WoS: 17Citation - Scopus: 23Search for R-Parity Violating Supersymmetry in Pp Collisions at S=13tev Using B Jets in a Final State With a Single Lepton, Many Jets, and High Sum of Large-Radius Jet Masses(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerResults are reported from a search for physics beyond the standard model in proton–proton collisions at a center-of-mass energy of s=13TeV. The search uses a signature of a single lepton, large jet and bottom quark jet multiplicities, and high sum of large-radius jet masses, without any requirement on the missing transverse momentum in an event. The data sample corresponds to an integrated luminosity of 35.9 fb−1 recorded by the CMS experiment at the LHC. No significant excess beyond the prediction from standard model processes is observed. The results are interpreted in terms of upper limits on the production cross section for R-parity violating supersymmetric extensions of the standard model using a benchmark model of gluino pair production, in which each gluino decays promptly via g˜→tbs. Gluinos with a mass below 1610 GeV are excluded at 95% confidence level.Article Citation - WoS: 51Citation - Scopus: 100Search for Vector-Like T and B Quark Pairs in Final States With Leptons at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerA search is presented for pair production of heavy vector-like T and B quarks in proton-proton collisions at s=13 TeV. The data sample corresponds to an integrated luminosity of 35.9 fb−1, collected with the CMS detector at the CERN LHC in 2016. Pair production of T quarks would result in a wide range of final states, since vector-like T quarks of charge 2e/3 are predicted to decay to bW, tZ, and tH. Likewise, vector-like B quarks are predicted to decay to tW, bZ, and bH. Three channels are considered, corresponding to final states with a single lepton, two leptons with the same sign of the electric charge, or at least three leptons. The results exclude T quarks with masses below 1140–1300 GeV and B quarks with masses below 910–1240 GeV for various branching fraction combinations, extending the reach of previous CMS searches by 200–600 GeV.Article Citation - WoS: 82Citation - Scopus: 119Search for New Physics in Events With Two Soft Oppositely Charged Leptons and Missing Transverse Momentum in Proton–proton Collisions at S=13 Tev(Elsevier Ltd., 2018) CMS Collaboration; Karapınar, GülerA search is presented for new physics in events with two low-momentum, oppositely charged leptons (electrons or muons) and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data collected using the CMS detector at the LHC correspond to an integrated luminosity of 35.9fb−1. The observed event yields are consistent with the expectations from the standard model. The results are interpreted in terms of pair production of charginos and neutralinos (χ˜1 ± and χ˜2 0) with nearly degenerate masses, as expected in natural supersymmetry models with light higgsinos, as well as in terms of the pair production of top squarks (t˜), when the lightest neutralino and the top squark have similar masses. At 95% confidence level, wino-like χ˜1 ±/χ˜2 0 masses are excluded up to 230 GeV for a mass difference of 20 GeV relative to the lightest neutralino. In the higgsino-like model, masses are excluded up to 168 GeV for the same mass difference. For t˜ pair production, top squark masses up to 450 GeV are excluded for a mass difference of 40 GeV relative to the lightest neutralino.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: 45Citation - Scopus: 53Search for Lepton Flavour Violating Decays of the Higgs Boson To Μ? and E? in Proton-Proton Collisions at ?s=13 Tev(Springer Verlag, 2018) Karapınar, GülerA search for lepton flavour violating decays of the Higgs boson in the μτ and eτ decay modes is presented. The search is based on a data set corresponding to an integrated luminosity of 35.9 fb−1 of proton-proton collisions collected with the CMS detector in 2016, at a centre-of-mass energy of 13 TeV. No significant excess over the standard model expectation is observed. The observed (expected) upper limits on the lepton flavour violating branching fractions of the Higgs boson are ℬ(H → μτ) < 0.25% (0.25%) and ℬ(H → eτ) < 0.61% (0.37%), at 95% confidence level. These results are used to derive upper limits on the off-diagonal μτ and eτ Yukawa couplings |Yμτ|2+|Yτμ|2<1.43×10−3 and |Yeτ|2+|Yτe|2<2.26×10−3 at 95% confidence level. The limits on the lepton flavour violating branching fractions of the Higgs boson and on the associated Yukawa couplings are the most stringent to date.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: 15Citation - Scopus: 48Measurement of Normalized Differential T T ¯ Cross Sections in the Dilepton Channel From Pp Collisions at ?s=13 Tev(Springer Verlag, 2018) CMS Collaboration; Karapınar, GülerNormalized differential cross sections for top quark pair production are measured in the dilepton (e+e−, μ+μ−, and μ∓e±) decay channels in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurements are performed with data corresponding to an integrated luminosity of 2.1 fb−1 using the CMS detector at the LHC. The cross sections are measured differentially as a function of the kinematic properties of the leptons, jets from bottom quark hadronization, top quarks, and top quark pairs at the particle and parton levels. The results are compared to several Monte Carlo generators that implement calculations up to next-to-leading order in perturbative quantum chromodynamics interfaced with parton showering, and also to fixed-order theoretical calculations of top quark pair production up to next-to-next-to-leading order.Article Citation - WoS: 13Citation - Scopus: 14Search for R-Parity Violating Decays of a Top Squark in Proton–proton Collisions at √s=8 Tev(Elsevier B.V., 2016) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Gomez, G.The results of a search for a supersymmetric partner of the top quark (top squark), pair-produced in proton–proton collisions at s=8 TeV, are presented. The search, which focuses on R-parity violating, chargino-mediated decays of the top squark, is performed in final states with low missing transverse momentum, two oppositely charged electrons or muons, and at least five jets. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb−1 collected with the CMS detector at the LHC in 2012. The data are found to be in agreement with the standard model expectation, and upper limits are placed on the top squark pair production cross section at 95% confidence level. Assuming a 100% branching fraction for the top squark decay chain, t˜→tχ˜1 ±,χ˜1 ±→ℓ±+jj, top squark masses less than 890 (1000) GeV for the electron (muon) channel are excluded for the first time in models with a single nonzero R-parity violating coupling λijk ′ (i,j,k≤2), where i,j,k correspond to the three generations. © 2016 The Author(s)Article Citation - WoS: 22Citation - Scopus: 21Search for Stealth Supersymmetry in Events With Jets, Either Photons or Leptons, and Low Missing Transverse Momentum in Pp Collisions at 8 Tev(Elsevier Ltd., 2015) CMS Collaboration; Karapınar, GülerThe results of a search for new physics in final states with jets, either photons or leptons, and low missing transverse momentum are reported. The study is based on a sample of proton-proton collisions collected at a center-of-mass energy s=8 TeV with the CMS detector in 2012. The integrated luminosity of the sample is 19.7 fb-1. Many models of new physics predict the production of events with jets, electroweak gauge bosons, and little or no missing transverse momentum. Examples include stealth models of supersymmetry (SUSY), which predict a hidden sector at the electroweak energy scale in which SUSY is approximately conserved. The data are used to search for stealth SUSY signatures in final states with either two photons or an oppositely charged electron and muon. No excess is observed with respect to the standard model expectation, and the results are used to set limits on squark pair production in the stealth SUSY framework. © 2015 The Authors.