WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 54Citation - Scopus: 59Measurement of the WZ Production Cross Section in pp Collisions at S=13 TeV(Elsevier, 2017) Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Woods, N.The WZ production cross section in proton-proton collisions at root s = 13 Tev is measured with the CMS experiment at the LHC using a data sample corresponding to an integrated luminosity of 2.3 fb(-1). The measurement is performed in the leptonic decay modes WZ -> lVl'l', where l,l'=e,mu. The measured cross section for the range 60<m (l'l') <120 GeV is sigma(pp -> WZ) = 39.9 +/- 3.2(stat)(2.9)(-3.1)(syst)+/- 0.4(theo)+/- 1.3(lumi)pb, consistent with the standard model prediction.Article Citation - WoS: 7Observation of Same-Sign Ww Production From Double Parton Scattering in Proton-Proton Collisions at P S=13 Tev(Amer Physical Soc, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Dragicevic, M.; Del Valle, EscalanteThe first observation of the production of (WW +/-)-W-+/- bosons from double parton scattering processes using same-sign electron-muon and dimuon events in proton-proton collisions is reported. The data sample corresponds to an integrated luminosity of 138 fb(-1 )recorded at a center-of-mass energy of 13 TeV using the CMS detector at the CERN LHC. Multivariate discriminants are used to distinguish the signal process from the main backgrounds. A binned maximum likelihood fit is performed to extract the signal cross section. The measured cross section for production of same-sign W bosons decaying leptonically is 80.7 +/- 11.2(stat)( -8.6)(+9.5)(syst) +/- 12.1(model) fb, whereas the measured fiducial cross section is 6.28 +/- 0.81(stat) +/- 0.69(syst) +/- 0.37(model) fb. The observed significance of the signal is 6.2 standard deviations above the background-only hypothesis.Article Two-Particle Azimuthal Correlations in Γp Interactions Using Ppb Collisions at √snn=8.16 Tev(ELSEVIER, 2023) Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Del Valle, A. Escalante; Fruehwirth, R.; Jeitler, M.The first measurements of the Fourier coefficients (V-n Delta) of the azimuthal distributions of charged hadrons emitted from photon-proton (gamma p) interactions are presented. The data are extracted from 68.8nb(-1) of ultra-peripheral proton-lead (pPb) collisions at root s(NN)= 8.16 TeV using the CMS detector. The high energy lead ions produce a flux of photons that can interact with the oncoming proton. This gamma p system provides a set of unique initial conditions with multiplicity lower than in photon-lead collisions but comparable to recent electron-positron and electron-proton data. The V-n Delta coefficients are presented in ranges of event multiplicity and transverse momentum (p(T)) and are compared to corresponding hadronic minimum bias pPb results. For a given multiplicity range, the mean p(T) of charged particles is smaller in gamma p than in pPb collisions. For both the gamma p and pPb samples, V-1 Delta is negative, V-2 Delta is positive, and V-3 Delta consistent with 0. For each multiplicity and p(T) range, V-2 Delta is larger for gamma p events. The gamma p data are consistent with model predictions that have no collective effects. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).Article Citation - WoS: 20Citation - Scopus: 28Measurement of Ckm Matrix Elements in Single Top Quark T-Channel Production in Proton-Proton Collisions at S=13 Tev(Elsevier B.V., 2020) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Dragicevic, M.; Sobol, A.The first direct, model-independent measurement is presented of the modulus of the Cabibbo–Kobayashi–Maskawa (CKM) matrix elements |η|Vtb, |η|Vtd, and |η|Vts, in final states enriched in single top quark t-channel events. The analysis uses proton-proton collision data from the LHC, collected during 2016 by the CMS experiment, at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Processes directly sensitive to these matrix elements are considered at both the production and decay vertices of the top quark. In the standard model hypothesis of CKM unitarity, a lower limit of |η|Vtb>0.970 is measured at the 95% confidence level. Several theories beyond the standard model are considered, and by releasing all constraints among the involved parameters, the values |η|Vtb=0.988±0.024, and |η|Vtd 2+|η|Vts 2=0.06±0.06, where the uncertainties include both statistical and systematic components, are measured. © 2020 The AuthorArticle 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: 8Citation - Scopus: 10ϒ(ns) Polarizations Versus Particle Multiplicity in Pp Collisions at S=7 Tev(Elsevier B.V., 2016) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Flix, J.The polarizations of the ϒ(1S), ϒ(2S), and ϒ(3S) mesons are measured as a function of the charged particle multiplicity in proton–proton collisions at s=7 TeV. The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb−1. The results are extracted from the dimuon decay angular distributions, in two ranges of ϒ(nS) transverse momentum (10–15 and 15–35 GeV), and in the rapidity interval |y|>1.2. The results do not show significant changes from low- to high-multiplicity pp collisions, although large uncertainties preclude definite statements in the ϒ(2S) and ϒ(3S) cases. © 2016 The Author(s)Article Citation - WoS: 24Citation - Scopus: 22Search for Top Squark Pair Production in Compressed-Mass Scenarios in Proton-Proton Collisions at S=8 Tev Using the Αt Variable(Elsevier B.V., 2017) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Cabrillo, I.J.An inclusive search is performed for supersymmetry in final states containing jets and an apparent imbalance in transverse momentum, p→T miss, due to the production of unobserved weakly interacting particles in pp collisions at a centre-of-mass energy of 8 TeV. The data, recorded with the CMS detector at the CERN LHC, correspond to an integrated luminosity of 18.5 fb−1. The dimensionless kinematic variable αT is used to discriminate between events with genuine p→T miss associated with unobserved particles and spurious values of p→T miss arising from jet energy mismeasurements. No excess of event yields above the expected standard model backgrounds is observed. The results are interpreted in terms of constraints on the parameter space of several simplified models of supersymmetry that assume the pair production of top squarks. The search provides sensitivity to a broad range of top squark (t˜) decay modes, including the two-body decay t˜→cχ˜1°, where c is a charm quark and χ˜1° is the lightest neutralino, as well as the four-body decay t˜→bff¯′χ˜1°, where b is a bottom quark and f and f¯′ are fermions produced in the decay of an intermediate off-shell W boson. These modes dominate in scenarios in which the top squark and lightest neutralino are nearly degenerate in mass. For these modes, top squarks with masses as large as 260 and 225 GeV are excluded, respectively, for the two- and four-body decays. © 2017 The AuthorArticle Citation - WoS: 338Citation - Scopus: 288Evidence for Collectivity in Pp Collisions at the Lhc(Elsevier B.V., 2017) Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Dubinin, M.Measurements of two- and multi-particle angular correlations in pp collisions at s=5,7, and 13TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb−1 (5 TeV), 6.2pb−1 (7 TeV), and 0.7pb−1 (13 TeV), were collected using the CMS detector at the LHC. The second-order (v2) and third-order (v3) azimuthal anisotropy harmonics of unidentified charged particles, as well as v2 of KS 0 and Λ/Λ‾ particles, are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum. For high-multiplicity pp events, a mass ordering is observed for the v2 values of charged hadrons (mostly pions), KS 0, and Λ/Λ‾, with lighter particle species exhibiting a stronger azimuthal anisotropy signal below pT≈2GeV/c. For 13 TeV data, the v2 signals are also extracted from four- and six-particle correlations for the first time in pp collisions, with comparable magnitude to those from two-particle correlations. These observations are similar to those seen in pPb and PbPb collisions, and support the interpretation of a collective origin for the observed long-range correlations in high-multiplicity pp collisions. © 2016 The AuthorArticle Citation - WoS: 90Citation - Scopus: 107Suppression of ϒ(1s), ϒ(2s), and ϒ(3s) Quarkonium States in Pbpb Collisions at Snn=2.76tev(Elsevier B.V., 2017) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Gomez, G.The production yields of ϒ(1S), ϒ(2S), and ϒ(3S) quarkonium states are measured through their decays into muon pairs in the CMS detector, in PbPb and pp collisions at the centre-of-mass energy per nucleon pair of 2.76 TeV. The data correspond to integrated luminosities of 166μb−1 and 5.4pb−1 for PbPb and pp collisions, respectively. Differential production cross sections are reported as functions of ϒ rapidity y up to 2.4, and transverse momentum pT up to 20GeV/c. A strong centrality-dependent suppression is observed in PbPb relative to pp collisions, by factors of up to ≈2 and 8, for the ϒ(1S) and ϒ(2S) states, respectively. No significant dependence of this suppression is observed as a function of y or pT. The ϒ(3S) state is not observed in PbPb collisions, which corresponds to a suppression for the centrality-integrated data by at least a factor of ≈7 at a 95% confidence level. The observed suppression is in agreement with theoretical scenarios modeling the sequential melting of quarkonium states in a quark gluon plasma. © 2017 The Author(s)Article Citation - WoS: 6Citation - Scopus: 6Search for Supersymmetry in Events With Photons and Missing Transverse Energy in Pp Collisions at 13 Tev(Elsevier B.V., 2017) Khachatryan, V.; Sirunyan, A.M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Milosevic, J.The results of a search for new physics in final states with photons and missing transverse energy are reported. The study is based on a sample of proton–proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 fb−1. Final states with two photons and significant missing transverse energy are used to search for supersymmetric particles in models of supersymmetry (SUSY) with general gauge-mediated (GGM) supersymmetry breaking. No excess is observed with respect to the standard model expectation, and the results are used to set limits on gluino pair production and squark pair production in the GGM SUSY framework. Gluino masses below 1.65 TeV and squark masses below 1.37 TeV are excluded at a 95% confidence level. © 2017 The Author(s)