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Permanent URI for this collectionhttps://hdl.handle.net/11147/6849
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Article Citation - WoS: 29Citation - Scopus: 33Measurement of the Jet Mass in Highly Boosted T T ¯ Events From Pp Collisions at √s=8tev(Springer Nature, 2017) Sirunyan, A.M.; Karapınar, Güler; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Baillon, P.The first measurement of the jet mass mjet of top quark jets produced in t t ¯ events from pp collisions at s=8TeV is reported for the jet with the largest transverse momentum pT in highly boosted hadronic top quark decays. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.7fb-1. The measurement is performed in the lepton+jets channel in which the products of the semileptonic decay t → b W with W → ℓν where ℓ is an electron or muon, are used to select t t ¯ events with large Lorentz boosts. The products of the fully hadronic decay t → b W with W → q q ¯ ′ are reconstructed using a single Cambridge–Aachen jet with distance parameter R= 1.2 , and pT> 400 GeV. The t t ¯ cross section as a function of mjet is unfolded at the particle level and is used to test the modelling of highly boosted top quark production. The peak position of the mjet distribution is sensitive to the top quark mass mt, and the data are used to extract a value of mt to assess this sensitivity. © 2017, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 33Citation - Scopus: 45Measurement of the Triple-Differential Dijet Cross Section in Proton-Proton Collisions at √s=8tev and Constraints on Parton Distribution Functions(Springer Nature, 2017) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Barney, D.A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8TeV using 19.7fb-1 of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is αS(MZ)=0.1199±0.0015(exp)-0.0020+0.0031(theo), where MZ is the mass of the Z boson. © 2017, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 59Citation - Scopus: 73Cross Section Measurement of T-Channel Single Top Quark Production in Pp Collisions at S=13tev(Elsevier B.V., 2017) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Rodrigo, T.The cross section for the production of single top quarks in the t channel is measured in proton–proton collisions at 13TeV with the CMS detector at the LHC. The analyzed data correspond to an integrated luminosity of 2.2fb−1. The event selection requires one muon and two jets where one of the jets is identified as originating from a bottom quark. Several kinematic variables are then combined into a multivariate discriminator to distinguish signal from background events. A fit to the distribution of the discriminating variable yields a total cross section of 238±13(stat)±29(syst) pb and a ratio of top quark and top antiquark production of Rt-ch.=1.81±0.18(stat)±0.15(syst). From the total cross section the absolute value of the CKM matrix element Vtb is calculated to be 1.05±0.07(exp)±0.02(theo). All results are in agreement with the standard model predictions. © 2017 The Author(s)Article Citation - WoS: 22Citation - Scopus: 26Search for Black Holes and Other New Phenomena in High-Multiplicity Final States in Proton-Proton Collisions at Root S=13 Tev(Elsevier Ltd., 2017) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Karapınar, Güler; CMS CollaborationA search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 fb(-1). The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data. (c) 2017 The Author(s). Published by Elsevier B.V.Article Citation - WoS: 13Citation - Scopus: 15Study of Dijet Events With a Large Rapidity Gap Between the Two Leading Jets in Pp Collisions at √s=7tev(Springer Nature, 2018) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Bloch, P.Events with no charged particles produced between the two leading jets are studied in proton-proton collisions at s=7TeV. The jets were required to have transverse momentum pTjet>40GeV and pseudorapidity 1.5 < | ηjet| < 4.7 , and to have values of ηjet with opposite signs. The data used for this study were collected with the CMS detector during low-luminosity running at the LHC, and correspond to an integrated luminosity of 8pb-1. Events with no charged particles with pT> 0.2 GeV in the interval - 1 < η< 1 between the jets are observed in excess of calculations that assume no color-singlet exchange. The fraction of events with such a rapidity gap, amounting to 0.5–1% of the selected dijet sample, is measured as a function of the pT of the second-leading jet and of the rapidity separation between the jets. The data are compared to previous measurements at the Tevatron, and to perturbative quantum chromodynamics calculations based on the Balitsky–Fadin–Kuraev–Lipatov evolution equations, including different models of the non-perturbative gap survival probability. © 2018, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 3Citation - Scopus: 6Combined Search for Supersymmetry With Photons in Proton-Proton Collisions at S=13 Tev(Elsevier B.V., 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Skovpen, Y.A combination of four searches for new physics involving signatures with at least one photon and large missing transverse momentum, motivated by generalized models of gauge-mediated supersymmetry (SUSY) breaking, is presented. All searches make use of proton-proton collision data at s=13 TeV, which were recorded with the CMS detector at the LHC in 2016, and correspond to an integrated luminosity of 35.9 fb−1. Signatures with at least one photon and large missing transverse momentum are categorized into events with two isolated photons, events with a lepton and a photon, events with additional jets, and events with at least one high-energy photon. No excess of events is observed beyond expectations from standard model processes, and limits are set in the context of gauge-mediated SUSY. Compared to the individual searches, the combination extends the sensitivity to gauge-mediated SUSY in both electroweak and strong production scenarios by up to 100 GeV in neutralino and chargino masses, and yields the first CMS result combining various SUSY searches in events with photons at s=13 TeV. © 2019 The Author(s)Article Citation - WoS: 22Citation - Scopus: 30Evidence for Ww Production From Double-Parton Interactions in Proton–proton Collisions at √s=13tev(Springer Nature, 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Snigirev, A.A search for WW production from double-parton scattering processes using same-charge electron-muon and dimuon events is reported, based on proton-proton collision data collected at a center-of-mass energy of 13TeV. The analyzed data set corresponds to an integrated luminosity of 77.4fb-1, collected using the CMS detector at the LHC in 2016 and 2017. Multivariate classifiers are used to discriminate between the signal and the dominant background processes. A maximum likelihood fit is performed to extract the signal cross section. This leads to the first evidence for WW production via double-parton scattering, with a significance of 3.9 standard deviations. The measured inclusive cross section is 1.41±0.28(stat)±0.28(syst)pb. © 2020, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 34Citation - Scopus: 41A Multi-Dimensional Search for New Heavy Resonances Decaying To Boosted Ww , Wz , or Zz Boson Pairs in the Dijet Final State at 13 Te(Springer Nature, 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Mandrik, P.A search in an all-jet final state for new massive resonances decaying to WW, WZ, or ZZ boson pairs using a novel analysis method is presented. The analysis is performed on data corresponding to an integrated luminosity of 77.3 fb-1 recorded with the CMS experiment at the LHC at a centre-of-mass energy of 13 Te. The search is focussed on potential narrow-width resonances with masses above 1.2 Te, where the decay products of each W or Z boson are expected to be collimated into a single, large-radius jet. The signal is extracted using a three-dimensional maximum likelihood fit of the two jet masses and the dijet invariant mass, yielding an improvement in sensitivity of up to 30% relative to previous search methods. No excess is observed above the estimated standard model background. In a heavy vector triplet model, spin-1 Z ′ and W ′ resonances with masses below 3.5 and 3.8 Te, respectively, are excluded at 95% confidence level. In a bulk graviton model, upper limits on cross sections are set between 27 and 0.2 fb for resonance masses between 1.2 and 5.2 Te, respectively. The limits presented in this paper are the best to date in the dijet final state. © 2020, CERN for the benefit of the CMS collaboration.Article Citation - WoS: 9Citation - Scopus: 70Production of Λc + Baryons in Proton-Proton and Lead-Lead Collisions at S =5.02tev(Elsevier B.V., 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Alcaraz Maestre, J.The transverse momentum (pT) spectra of inclusively produced Λc + baryons are measured via the exclusive decay channel Λc +→pK−π+ using the CMS detector at the LHC. Spectra are measured as a function of transverse momentum in proton-proton (pp) and lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measurement is performed within the Λc + rapidity interval |y|<1 in the pT range of 5–20GeV/c in pp and 10–20GeV/c in PbPb collisions. The observed yields of Λc + for pT of 10–20GeV/c suggest a suppression in central PbPb collisions compared to pp collisions scaled by the number of nucleon-nucleon (NN) interactions. The Λc +/D0 production ratio in pp collisions is compared to theoretical models. In PbPb collisions, this ratio is consistent with the result from pp collisions in their common pT range. © 2020 The Author(s)Article Citation - WoS: 32Citation - Scopus: 49Measurement of the tt‾bb‾ Production Cross Section in the All-Jet Final State in pp Collisions at S=13 TeV(Elsevier B.V., 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Brandstetter, J.; Moraes, A.A measurement of the production cross section of top quark pairs in association with two b jets (tt‾bb‾) is presented using data collected in proton-proton collisions at s=13 TeV by the CMS detector at the LHC corresponding to an integrated luminosity of 35.9 fb−1. The cross section is measured in the all-jet decay channel of the top quark pair by selecting events containing at least eight jets, of which at least two are identified as originating from the hadronization of b quarks. A combination of multivariate analysis techniques is used to reduce the large background from multijet events not containing a top quark pair, and to help discriminate between jets originating from top quark decays and other additional jets. The cross section is determined for the total phase space to be 5.5±0.3(stat)<inf>−1.3</inf> +1.6(syst)pb and also measured for two fiducial tt‾bb‾ definitions. The measured cross sections are found to be larger than theoretical predictions by a factor of 1.5–2.4, corresponding to 1–2 standard deviations. © 2020 The Author