Browsing by Subject "TOP-PAIR"

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  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Talvitie, J.; Tuuva, T. (2018)
    The cross sections for the production of t (t) over bar b (b) over bar and t (t) over bar jj events and their ratio sigma(t (t) over bar b (b) over bar)/sigma(t (t) over bar jj) are measured using data corresponding to an integrated luminosity of 2.3 fb(-1) collected in pp collisions at root s = 13 TeV with the CMS detector at the LHC. Events with two leptons (e or mu) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. In the full phase space, the measured ratio is 0.022 +/- 0.003 (stat) +/- 0.006 (syst), the cross section sigma(t (t) over bar b (b) over bar) bis 4.0 +/- 0.6 (stat)+/- 1.3 (syst) pb and sigma(t (t) over bar jj) is 184 +/- 6 (stat)+/- 33 (syst) pb. The measurements are compared with the standard model expectations obtained from a POWHEG simulation at next-to-leading-order interfaced with PYTHIA. (c) 2017 The Author. Published by Elsevier B.V.
  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T. (2019)
    A search for a heavy resonance decaying into a top quark and antiquark (tt) pair is performed using proton-proton collisions at p s = 13TeV. The search uses the data set collected with the CMS detector in 2016, which corresponds to an integrated luminosity of 35.9 fb. The analysis considers three exclusive fi nal states and uses reconstruction techniques that are optimized for top quarks with high Lorentz boosts, which requires the use of nonisolated leptons and jet substructure techniques. No signi fi cant excess of events relative to the expected yield from standard model processes is observed. Upper limits on the production cross section of heavy resonances decaying to a tt pair are calculated. Limits are derived for a leptophobic topcolor Z 0 resonance with widths of 1, 10, and 30%, relative to the mass of the resonance, and exclude masses up to 3.80, 5.25, and 6.65TeV, respectively. Kaluza-Klein excitations of the gluon in the Randall-Sundrum model are excluded up to 4.55TeV. To date, these are the most stringent limits on tt resonances.