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Sirunyan, A.M.,Tumasyan, A. Elsevier 2017 Physics letters: B Vol.774 No.-
<P><B>Abstract</B></P> <P>A statistical combination of searches is presented for massive resonances decaying to WW, WZ, ZZ, WH, and ZH boson pairs in proton–proton collision data collected by the CMS experiment at the LHC. The data were taken at centre-of-mass energies of 8 and 13 TeV, corresponding to respective integrated luminosities of 19.7 and up to 2.7 fb<SUP>−1</SUP>. The results are interpreted in the context of heavy vector triplet and singlet models that mimic properties of composite-Higgs models predicting W′ and Z′ bosons decaying to WZ, WW, WH, and ZH bosons. A model with a bulk graviton that decays into WW and ZZ is also considered. This is the first combined search for WW, WZ, WH, and ZH resonances and yields lower limits on masses at 95% confidence level for W′ and Z′ singlets at 2.3 TeV, and for a triplet at 2.4 TeV. The limits on the production cross section of a narrow bulk graviton resonance with the curvature scale of the warped extra dimension k ˜ = 0.5 , in the mass range of 0.6 to 4.0 TeV, are the most stringent published to date.</P>
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Hartl, C.,Hö,rmann, N Springer-Verlag 2017 Journal of high energy physics Vol.2017 No.5
<P>A search for single production of vector-like quarks, T and B, decaying into a Z boson and a top or a bottom quark, respectively, is presented. The search is performed using data collected by the CMS experiment at the LHC in proton-proton collisions at root s = 13TeV, corresponding to an integrated luminosity of 2.3 fb(-1). An exotic T quark production mode through the decay of a heavy Z' resonance is also considered. The search is performed in events with a Z boson decaying leptonically, accompanied by a bottom or a top quark decaying hadronically. No excess of events is observed over the standard model background expectation. Products of production cross section and branching fraction for T and B quarks from 1.26 and 0.13 pb are excluded at 95% confidence level for the range of resonance mass considered, which is between 0.7 and 1.7TeV. Limits on the product of the Z 0 boson production cross section and branching fraction, with the Z' boson decaying to the Tt final state, are set between 0.31 and 0.13 pb, for Z' boson masses in the range from 1.5 to 2.5 TeV. This is the first search at 13TeV for single production of vector-like quarks in events with a Z boson decaying leptonically accompanied by boosted jets.</P>
Sirunyan, A.M.,Tumasyan, A. North-Holland Pub. Co 2019 Physics letters. Section B Vol.791 No.-
<P><B>Abstract</B></P> <P>Measurements of the production of the standard model Higgs boson decaying to a W boson pair are reported. The <SUP> W + </SUP> <SUP> W − </SUP> candidates are selected in events with an oppositely charged lepton pair, large missing transverse momentum, and various numbers of jets. To select Higgs bosons produced via vector boson fusion and associated production with a W or Z boson, events with two jets or three or four leptons are also selected. The event sample corresponds to an integrated luminosity of 35.9 <SUP> fb − 1 </SUP> , collected in p p collisions at s = 13 TeV by the CMS detector at the LHC during 2016. Combining all channels, the observed cross section times branching fraction is 1.28 − 0.17 + 0.18 times the standard model prediction for the Higgs boson with a mass of 125.09 GeV . This is the first observation of the Higgs boson decay to W boson pairs by the CMS experiment.</P>
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Ambrogi, F.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Grossmann, J. Institute of Physics Pub 2018 The journal of high energy physics Vol.2018 No.3
<P>Results are presented from a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more leptons, which can include up to two hadronically decaying tau leptons. The results are based on a sample of proton proton collision data collected at root s = 13 TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb(-1). The observed event yields are consistent with the expectations based on the standard model. The results are interpreted in simplified models of supersymmetry describing various scenarios for the production and decay of charginos and neutralinos. Depending on the model parameters chosen, mass values between 180 GeV and 1150 GeV are excluded at 95% CL. These results significantly extend the parameter space probed for these particles in searches at the LHC. In addition, results are presented in a form suitable for alternative theoretical interpretations.</P>
Observation of the χb1(3P) and χb2(3P) and Measurement of their Masses
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Ambrogi, F.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Dragicevic, M.,Erö,, J.,Escalante Del Valle, A.,Flechl, M.,Frü,hwirth, R.,Ghete, V. M.,Hrubec, J.,Jei American Physical Society 2018 Physical Review Letters Vol.121 No.9
<P>The chi(b1)(3P) and chi(b2)(3P) states are observed through their gamma(3S)(gamma) decays, using an event sample of proton-proton collisions collected by the CMS experiment at the CERN LHC. The data were collected at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 80.0 fb(-1). The gamma(3S) mesons are identified through their dimuon decay channel, while the low-energy photons are detected after converting to e(+)e(-) pairs in the silicon tracker, leading to a chi(b)(3P) mass resolution of 2.2 MeV. This is the first time that the J = 1 and 2 states are well resolved and their masses individually measured: 10513.42 +/- 0.41(stat) +/- 0.18(syst) MeV and 10524.02 +/- 0.57(stat) +/- 0.18(syst) MeV; they are determined with respect to the world-average value of gamma(3S) mass, which has an uncertainty of 0.5 MeV. The mass splitting is measured to be 10.60 +/- 0.64(stat) +/- 0.17(syst) MeV.</P>
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Ambrogi, F.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Escalante Del Valle, A.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Gh American Physical Society 2018 Physical Review Letters Vol.120 No.24
<P>A search for physics beyond the standard model in events with one or more high-momentum Higgs bosons, H, decaying to pairs of b quarks in association with missing transverse momentum is presented. The data, corresponding to an integrated luminosity of 35.9 fb(-1), were collected with the CMS detector at the LHC in proton-proton collisions at the center-of-mass energy root s = 13 TeV. The analysis utilizes a new b quark tagging technique based on jet substructure to identify jets from H -> b (b) over bar. Events are categorized by the multiplicity of H-tagged jets, jet mass, and the missing transverse momentum. No significant deviation from standard model expectations is observed. In the context of supersymmetry (SUSY), limits on the cross sections of pair-produced gluinos are set, assuming that gluinos decay to quark pairs, H (or Z), and the lightest SUSY particle, LSP, through an intermediate next-to-lightest SUSY particle, NLSP. With large mass splitting between the NLSP and LSP, and 100% NLSP branching fraction to H, the lower limit on the gluino mass is found to be 2010 GeV.</P>
Measurement of Prompt D0 Meson Azimuthal Anisotropy in Pb-Pb Collisions at sNN=5.02 TeV
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Ambrogi, F.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Grossmann, J. American Physical Society 2018 Physical Review Letters Vol.120 No.20
<P>The prompt D-0 meson azimuthal anisotropy coefficients, v(2) and ?v(3), are measured at midrapidity ( |y| < 1.0) in Pb-Pb collisions at a center-of-mass energy root s(NN) = 5.02 TeV per nucleon pair with data collected by the CMS experiment. The measurement is performed in the transverse momentum (p(T)) range of 1 to 40 GeV/c, for central and midcentral collisions. The v(2) coefficient is found to be positive throughout the p(T) range studied. The first measurement of the prompt D-0 meson v(3) coefficient is performed, and values up to 0.07 are observed for p(T) around 4 GeV/c. Compared to measurements of charged particles, a similar p(T) dependence, but smaller magnitude for p(T) < 6 GeV/r, is found for prompt D-0 meson v(2) and v(3) coefficients. The results are consistent with the presence of collective motion of charm quarks at low p(r) and a path length dependence of charm quark energy loss at high p(r), thereby providing new constraints on the theoretical description of the interactions between charm quarks and the quark-gluon plasma.</P>
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Hartl, C.,Hö,rmann, N Springer-Verlag 2017 European Physical Journal C Vol.77 No.12
<P>A search is presented for an excess of events with heavy-flavor quark pairs (t (t) over bar and b (b) over bar) and a large imbalance in transverse momentum in data from proton-proton collisions at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 2.2 fb(-1) collected with the CMS detector at the CERN LHC. No deviations are observed with respect to standard model predictions. The results are used in the first interpretation of dark matter production in t (t) over bar and b (b) over bar final states in a simplified model. This analysis is also the first to perform a statistical combination of searches for dark matter produced with different heavy-flavor final states. The combination provides exclusions that are stronger than those achieved with individual heavy-flavor final states.</P>
Suppression of Excited ϒ States Relative to the Ground State in Pb-Pb Collisions at sNN=5.02 TeV
Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Hartl, C.,Hö,rmann, N American Physical Society 2018 Physical Review Letters Vol.120 No.14
<P>The relative yields of gamma mesons produced in pp and Pb-Pb collisions at root s(NN) = 5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, gamma(2S) and gamma(3S), to the ground state, gamma(1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [gamma(nS)/gamma(1S)](Pb-Pb)/[gamma(nS)/gamma(1S)](PP), are measured to be 0.308 +/- 0.055(stat) +/- 0.019(syst) for the gamma(2S) and less than 0.26 at 95% confidence level for the gamma(3S). No significant gamma(3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as gamma transverse momentum and rapidity. No significant dependencies are observed.</P>