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  • Measurement of the $pp \to ZZ$ production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at $\sqrt s=$8 TeV
    Publication . CMS collaboration (2135 authors); Hollar, Jonathan; Nayak, Aruna; Calpas, Betty; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; Lloret Iglesias, Lara; David Tinoco Mendes, Andre; Musella, Pasquale; Silva, Pedro; Pela, Joao; Leonardo, Nuno
    A measurement of the inclusive ZZ production cross section and constraints on anomalous triple gauge couplings in proton–proton collisions at s=8 TeV are presented. The analysis is based on a data sample, corresponding to an integrated luminosity of 19.6 fb−1 , collected with the CMS experiment at the LHC. The measurements are performed in the leptonic decay modes ZZ→ℓℓℓ′ℓ′ , where ℓ=e,μ and ℓ′=e,μ,τ . The measured total cross section σ(pp→ZZ)=7.7±0.5 (stat)−0.4+0.5 (syst)±0.4(theo)±0.2 (lumi) pb , for both Z bosons produced in the mass range 60
    2014-11-30Journal article Open access Show more
  • Odd and even partial waves of $ηπ^−$ and $η′π^−$ in $π^−p → η^{(′)}π^−p$ at 191 GeV/c
    Publication . COMPASS collaboration (207 authors); Bordalo, P.; Franco, C.; Nunes, Ana Sofia; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M.
    Exclusive production of ηπ− and η′π− has been studied with a 191 GeV/c π− beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum ( L ) characteristics in the inspected invariant mass range up to 3 GeV/c2 . A striking similarity between the two systems is observed for the L=2,4,6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a2(1320) and a4(2040) are in line with this similarity. In contrast, a strong enhancement of η′π− over ηπ− is found for the L=1,3,5 waves, which carry non- qq¯ quantum numbers. The L=1 intensity peaks at 1.7 GeV/c2 in η′π− and at 1.4 GeV/c2 in ηπ− , the corresponding phase motions with respect to L=2 are different.
    2014-11-30Journal article Open access Show more