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Permanent URI for this collectionhttps://hdl.handle.net/11147/6849
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Article Citation - WoS: 105Evidence of B-Jet Quenching in PbPb Collisions at √sNN=2.76 TeV(American Physical Society, 2014) Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Smith, W. H.The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (p(T)) range of 80-250 GeV/c, and within pseudorapidity |eta| < 2. The nuclear modification factor (RAA) calculated from these spectra shows a strong suppression in the b-jet yield in PbPb collisions relative to the yield observed in pp collisions at the same energy. The suppression persists to the largest values of p(T) studied, and is centrality dependent. The R-AA is about 0.4 in the most central events, similar to previous observations for inclusive jets. This implies that jet quenching does not have a strong dependence on parton mass and flavor in the jet p(T) range studied.Article Citation - WoS: 205Citation - Scopus: 159Search for Resonances and Quantum Black Holes Using Dijet Mass Spectra in Proton-Proton Collisions at S =8tev(American Physical Society, 2015) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Hegeman, J.A search for resonances and quantum black holes is performed using the dijet mass spectra measured in proton-proton collisions at s=8TeV with the CMS detector at the LHC. The data set corresponds to an integrated luminosity of 19.7fb-1. In a search for narrow resonances that couple to quark-quark, quark-gluon, or gluon-gluon pairs, model-independent upper limits, at 95% confidence level, are obtained on the production cross section of resonances, with masses above 1.2 TeV. When interpreted in the context of specific models the limits exclude string resonances with masses below 5.0 TeV; excited quarks below 3.5 TeV; scalar diquarks below 4.7 TeV; W′ bosons below 1.9 TeV or between 2.0 and 2.2 TeV; Z′ bosons below 1.7 TeV; and Randall-Sundrum gravitons below 1.6 TeV. A separate search is conducted for narrow resonances that decay to final states including b quarks. The first exclusion limit is set for excited b quarks, with a lower mass limit between 1.2 and 1.6 TeV depending on their decay properties. Searches are also carried out for wide resonances, assuming for the first time width-to-mass ratios up to 30%, and for quantum black holes with a range of model parameters. The wide resonance search excludes axigluons and colorons with mass below 3.6 TeV, and color-octet scalars with mass below 2.5 TeV. Lower bounds between 5.0 and 6.3 TeV are set on the masses of quantum black holes. © 2015 CERN, for the CMS Collaboration.Article Citation - WoS: 72Citation - Scopus: 72Measurement of J /Ψ and Ψ (2s) Prompt Double-Differential Cross Sections in Pp Collisions at S =7tev(American Physical Society, 2015) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Innocente, V.The double-differential cross sections of promptly produced J/ψ and ψ(2S) mesons are measured in pp collisions at s=7TeV, as a function of transverse momentum pT and absolute rapidity |y|. The analysis uses J/ψ and ψ(2S) dimuon samples collected by the CMS experiment, corresponding to integrated luminosities of 4.55 and 4.90fb-1, respectively. The results are based on a two-dimensional analysis of the dimuon invariant mass and decay length, and extend to pT=120 and 100 GeV for the J/ψ and ψ(2S), respectively, when integrated over the interval |y|<1.2. The ratio of the ψ(2S) to J/ψ cross sections is also reported for |y|<1.2, over the range 10<pT<100GeV. These are the highest pT values for which the cross sections and ratio have been measured. © 2015 CERN, for the CMS Collaboration.Article Citation - WoS: 518Citation - Scopus: 550Precise Determination of the Mass of the Higgs Boson and Tests of Compatibility of Its Couplings With the Standard Model Predictions Using Proton Collisions at 7 and 8 Tev(Springer Nature, 2015) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Janot, P.Properties of the Higgs boson with mass near 125 GeV are measured in proton-proton collisions with the CMS experiment at the LHC. Comprehensive sets of production and decay measurements are combined. The decay channels include γγ, ZZ, WW, ττ, bb, and μμ pairs. The data samples were collected in 2011 and 2012 and correspond to integrated luminosities of up to 5.1fb-1at 7TeV and up to 19.7fb-1at 8 TeV. From the high-resolution γγ and ZZ channels, the mass of the Higgs boson is determined to be (Formula presented) GeV. For this mass value, the event yields obtained in the different analyses tagging specific decay channels and production mechanisms are consistent with those expected for the standard model Higgs boson. The combined best-fit signal relative to the standard model expectation is (Formula presented) at the measured mass. The couplings of the Higgs boson are probed for deviations in magnitude from the standard model predictions in multiple ways, including searches for invisible and undetected decays. No significant deviations are found. © 2015, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 1Citation - Scopus: 6Search for Supersymmetry With Photons in Pp Collisions at S =8tev(American Physical Society, 2015) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Calvo, E.Two searches for physics beyond the standard model in events containing photons are presented. The data sample used corresponds to an integrated luminosity of 19.7fb-1 of proton-proton collisions at s=8TeV, collected with the CMS experiment at the CERN LHC. The analyses pursue different inclusive search strategies. One analysis requires at least one photon, at least two jets, and a large amount of transverse momentum imbalance, while the other selects events with at least two photons and at least one jet, and uses the razor variables to search for signal events. The background expected from standard model processes is evaluated mainly from data. The results are interpreted in the context of general gauge-mediated supersymmetry, with the next-to-lightest supersymmetric particle either a bino- or wino-like neutralino, and within simplified model scenarios. Upper limits at the 95% confidence level are obtained for cross sections as functions of the masses of the intermediate supersymmetric particles. © 2015 CERN. © 2015 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the "http://creativecommons.org/licenses/by/3.0/" Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Erratum Citation - WoS: 15Citation - Scopus: 7Erratum To: Measurements of the Z→4ℓ Branching Fraction, and Constraints on Anomalous Triple Gauge Couplings at S=13tev (the European Physical Journal C, (2018), 78, 2, (165), 10.1140/Epjc(Springer Nature, 2018) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Virto, A.L.Reference [6]: “Phys. Lett. B 763, 280” should have been corrected into “Phys. Lett. B 763, 280 (2016)”. © 2018, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 65Citation - Scopus: 69Search for New Physics in Same-Sign Dilepton Events in Proton–proton Collisions at √s = 13 Tev(Springer Nature, 2016) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Scodellaro, L.A search for new physics is performed using events with two isolated same-sign leptons, two or more jets, and missing transverse momentum. The results are based on a sample of proton–proton collisions at a center-of-mass energy of 13TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb1. Multiple search regions are defined by classifying events in terms of missing transverse momentum, the scalar sum of jet transverse momenta, the transverse mass associated with a W boson candidate, the number of jets, the number of b quark jets, and the transverse momenta of the leptons in the event. The analysis is sensitive to a wide variety of possible signals beyond the standard model. No excess above the standard model background expectation is observed. Constraints are set on various supersymmetric models, with gluinos and bottom squarks excluded for masses up to 1300 and 680GeV, respectively, at the 95 % confidence level. Upper limits on the cross sections for the production of two top quark-antiquark pairs (119fb) and two same-sign top quarks (1.7pb) are also obtained. Selection efficiencies and model independent limits are provided to allow further interpretations of the results. © 2016, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 56Citation - Scopus: 60Search for Lepton Flavour Violating Decays of the Higgs Boson To Eτ and Eμ 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.; Trevisani, N.A direct search for lepton flavour violating decays of the Higgs boson (H) in the H→eτ and H→eμ channels is described. The data sample used in the search was collected in proton–proton collisions at s=8 TeV with the CMS detector at the LHC and corresponds to an integrated luminosity of 19.7 fb−1. No evidence is found for lepton flavour violating decays in either final state. Upper limits on the branching fractions, B(H→eτ)<0.69% and B(H→eμ)<0.035%, are set at the 95% confidence level. The constraint set on B(H→eτ) is an order of magnitude more stringent than the existing indirect limits. The limits are used to constrain the corresponding flavour violating Yukawa couplings, absent in the standard model. © 2016 The Author(s)Article Citation - WoS: 68Citation - Scopus: 73Measurement of the W +w - Cross Section in Pp Collisions at √s= 8 Tevand Limits on Anomalous Gauge Couplings(Springer Nature, 2016) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Albajar, C.A measurement of the W boson pair production cross section in proton-proton collisions at √s = 8 TeV is presented. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 19.4fb-1. The W +W - candidates are selected from events with two charged leptons, electrons or muons, and large missing transverse energy. The measured W +W - cross section is 60.1 ± 0.9 (stat) ± 3.2 (exp) ± 3.1 (theo) ± 1.6 (lumi) pb = 60.1±4.8 pb, consistent with the standard model prediction. The W +W - cross sections are also measured in two different fiducial phase space regions. The normalized differential cross section is measured as a function of kinematic variables of the final-state charged leptons and compared with several perturbative QCD predictions. Limits on anomalous gauge couplings associated with dimension-six operators are also given in the framework of an effective field theory. The corresponding 95 % confidence level intervals are -5.7<cWWW/Λ2<5.9TeV-2, -11.4<cW/Λ2<5.4TeV-2, -29.2<cB/Λ2<23.9TeV-2, in the HISZ basis. © 2016, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 42Citation - Scopus: 86Measurement of the Double-Differential Inclusive Jet Cross Section in Proton–proton Collisions at √s = 13 Tev(Springer Nature, 2016) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Matorras, F.A measurement of the double-differential inclusive jet cross section as a function of jet transverse momentum pT and absolute jet rapidity | y| is presented. The analysis is based on proton–proton collisions collected by the CMS experiment at the LHC at a centre-of-mass energy of 13TeV. The data samples correspond to integrated luminosities of 71 and 44pb-1 for | y| < 3 and 3.2 < | y| < 4.7 , respectively. Jets are reconstructed with the anti-kt clustering algorithm for two jet sizes, R, of 0.7 and 0.4, in a phase space region covering jet pT up to 2TeV and jet rapidity up to | y| = 4.7. Predictions of perturbative quantum chromodynamics at next-to-leading order precision, complemented with electroweak and nonperturbative corrections, are used to compute the absolute scale and the shape of the inclusive jet cross section. The cross section difference in R, when going to a smaller jet size of 0.4, is best described by Monte Carlo event generators with next-to-leading order predictions matched to parton showering, hadronisation, and multiparton interactions. In the phase space accessible with the new data, this measurement provides a first indication that jet physics is as well understood at s=13TeV as at smaller centre-of-mass energies. © 2016, CERN for the benefit of the CMS collaboration.