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Khachatryan, V.,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. Institute of Physics Pub 2017 The journal of high energy physics Vol.2017 No.1
<P>This paper describes the search for a high-mass narrow-width scalar particle decaying into a Z boson and a photon. The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at center-of-mass energies of 8 and 13TeV, corresponding to integrated luminosities of 19.7 and 2.7 fb(-1), respectively. The Z bosons are reconstructed from opposite-sign electron or muon pairs. No statistically signi fi cant deviation from the standard model predictions has been found in the 200-2000 GeV mass range. Upper limits at 95% con fi dence level have been derived on the product of the scalar particle production cross section and the branching fraction of the Z decaying into electrons or muons, which range from 280 to 20 fb for resonance masses between 200 and 2000 GeV.</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.6
<P>A search for lepton flavour violating decays of the Higgs boson in the mu tau and e tau 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 -> mu tau) < 0.25% (0.25%) and B(H -> e tau) < 0.61% (0.37%), at 95% confidence level. These results are used to derive upper limits on the off-diagonal mu tau and e tau Yukawa couplings root vertical bar Y-mu tau vertical bar(2) + vertical bar Y-mu tau vertical bar(2) < 1.43 x 10(-3) and root vertical bar Y-e tau vertical bar(2) + vertical bar Y-tau e vertical bar(2) < 2.26 x 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.</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 Institute of Physics Pub 2018 The journal of high energy physics Vol.2018 No.5
<P>A search for a heavy right-handed W boson (W-R) decaying to a heavy right-handed neutrino and a charged lepton in events with two same-flavor leptons (e or mu) 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 N-R contributes significantly to the W-R decay width, the region in the two-dimensional (m(WR), m(NR)) mass plane excluded at 95% confidence level extends to approximately m(WR) = 4 : 4TeV and covers a large range of right-handed neutrino masses below the W-R boson mass. This analysis provides the most stringent limits on the W-R mass to date.</P>
Khachatryan, V.,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. Springer Berlin Heidelberg 2017 The European physical journal. C, Particles and fi Vol.77 No.4
<P>The nuclear modification factor [FORMULA OMISSION] and the azimuthal anisotropy coefficient [FORMULA OMISSION] of prompt and nonprompt (i.e. those from decays of b hadrons) [FORMULA OMISSION] mesons, measured from PbPb and pp collisions at [FORMULA OMISSION][FORMULA OMISSION] at the LHC, are reported. The results are presented in several event centrality intervals and several kinematic regions, for transverse momenta [FORMULA OMISSION][FORMULA OMISSION] and rapidity [FORMULA OMISSION], extending down to [FORMULA OMISSION][FORMULA OMISSION] in the [FORMULA OMISSION] range. The [FORMULA OMISSION] of prompt [FORMULA OMISSION] is found to be nonzero, but with no strong dependence on centrality, rapidity, or [FORMULA OMISSION] over the full kinematic range studied. The measured [FORMULA OMISSION] of nonprompt [FORMULA OMISSION] is consistent with zero. The [FORMULA OMISSION] of prompt [FORMULA OMISSION] exhibits a suppression that increases from peripheral to central collisions but does not vary strongly as a function of either <I>y</I> or [FORMULA OMISSION] in the fiducial range. The nonprompt [FORMULA OMISSION][FORMULA OMISSION] shows a suppression which becomes stronger as rapidity or [FORMULA OMISSION] increases. The [FORMULA OMISSION] and [FORMULA OMISSION] of open and hidden charm, and of open charm and beauty, are compared.</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. Springer-Verlag 2018 Journal of high energy physics Vol.2018 No.4
<P>Normalized differential cross sections for top quark pair production are measured in the dilepton (e(+)e(-), mu(+)mu(-), and mu(-/+),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.</P>
Study of Jet Quenching with Z+jet Correlations in Pb-Pb and pp 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 2017 Physical review letters Vol.119 No.8
<P>The production of jets in association with Z bosons, reconstructed via the mu(+)mu(-) and e(+)e(-) decay channels, is studied in pp and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%-30% centrality range. The back-to-back azimuthal alignment was studied in both pp and Pb-Pb collisions for Z bosons with transverse momentum p(T)(Z) > 60 GeV/c and a recoiling jet with p(T)(jet) > 30 GeV/c. The p(T) imbalance x(jZ) = p(T)(jet)/p(T)(Z), as well as the average number of jet partners per Z, R-jZ, was studied in intervals of p(T)(Z). The R-jZ is found to be smaller in Pb-Pb than in pp collisions, which suggests that in Pb-Pb collisions a larger fraction of partons associated with the Z bosons fall below the 30 GeV/c p(T)(jet) threshold because they lose energy.</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 Institute of Physics Pub 2018 The journal of high energy physics Vol.2018 No.7
<P>The process pp -> pl(+)l(-)p(()*()), with l(+)l(-) a muon or an electron pair produced at midrapidity with mass larger than 110 GeV, has been observed for the first time at the LHC in pp collisions at root s = 13 TeV. One of the two scattered protons is measured in the CMS-TOTEM precision proton spectrometer (CT-PPS), which operated for the first time in 2016. The second proton either remains intact or is excited and then dissociates into a low-mass state p*, which is undetected. The measurement is based on an integrated luminosity of 9.4 fb(-1) collected during standard, high-luminosity LHC operation. A total of 12 mu(+)/mu(-) and 8 e(+)e(-) pairs with m(l(+)l(-)) > 110 GeV, and matching forward proton kinematics, are observed, with expected backgrounds of 1.49 +/- 0.07 (stat) +/- 0.53 (syst) and 2.36 +/- 0.09 (stat) +/- 0.47(syst), respectively. This corresponds to an excess of more than five standard deviations over the expected background. The present result constitutes the first observation of proton-tagged gamma gamma collisions at the electroweak scale. This measurement also demonstrates that CT-PPS performs according to the design specifications.</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 Springer-Verlag 2018 Journal of high energy physics Vol.2018 No.9
<P>A search has been performed for heavy resonances decaying to ZZ or ZW in 2l2q final states, with two charged leptons (l = e, mu) produced by the decay of a Z boson, and two quarks produced by the decay of a W or Z boson. The analysis is sensitive to resonances with masses in the range from 400 to 4500 GeV. Two categories are defined based on the merged or resolved reconstruction of the hadronically decaying vector boson, optimized for high- and low-mass resonances, respectively. The search is based on data collected during 2016 by the CMS experiment at the LHC in proton-proton collisions with a center-of-mass energy of root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). No excess is observed in the data above the standard model background expectation. Upper limits on the production cross section of heavy, narrow spin-1 and spin-2 resonances are derived as a function of the resonance mass, and exclusion limits on the production of W' bosons and bulk graviton particles are calculated in the framework of the heavy vector triplet model and warped extra dimensions, respectively.</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 Institute of Physics Pub 2018 The journal of high energy physics Vol.2018 No.6
<P>A search for a new scalar resonance decaying to a pair of Z bosons is performed in the mass range from 130 GeV to 3TeV, and for various width scenarios. The analysis is based on proton-proton collisions recorded by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb(-1) at a center-of-mass energy of 13TeV. The Z boson pair decays are reconstructed using the 4l, 2l2q, and 2l2 nu final states, where l = e or mu. Both gluon fusion and electroweak production of the scalar resonance are considered, with a free parameter describing their relative cross sections. A dedicated categorization of events, based on the kinematic properties of associated jets, and matrix element techniques are employed for an optimal signal and background separation. A description of the interference between signal and background amplitudes for a resonance of an arbitrary width is included. No significant excess of events with respect to the standard model expectation is observed and limits are set on the product of the cross section for a new scalar boson and the branching fraction for its decay to ZZ for a large range of masses and widths.</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 Institute of Physics Pub 2018 The journal of high energy physics Vol.2018 No.5
<P>A search for a new heavy particle decaying to a pair of vector bosons (WW or WZ) is presented using data from the CMS detector corresponding to an integrated luminosity of 35.9 fb(-1) collected in proton-proton collisions at a centre-of-mass energy of 13 TeV in 2016. One of the bosons is required to be a W boson decaying to e nu or mu nu, while the other boson is required to be reconstructed as a single massive jet with substructure compatible with that of a highly-energetic quark pair from a W or Z boson decay. The search is performed in the resonance mass range between 1.0 and 4.4 TeV. The largest deviation from the background-only hypothesis is observed for a mass near 1.4 TeV and corresponds to a local significance of 2.5 standard deviations. The result is interpreted as an upper bound on the resonance production cross section. Comparing the excluded cross section values and the expectations from theoretical calculations in the bulk graviton and heavy vector triplet models, spin-2 WW resonances with mass smaller than 1.07 TeV and spin-1 WZ resonances lighter than 3.05 TeV, respectively, are excluded at 95% confidence level.</P>