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Ali, S; Andreotti, M; Back, J J; Barter, W; Bel, L J; Belloli, N; Belyaev, I; Bertholet, E; Betti, F; Bezshyiko, Ia; Bjørn, M; Borghi, S; Bowen, E; Byczynski, W; Camboni, A; Cenci, R; Closier, J; Cogneras, E; Da Cunha Marinho, F; Dall'Occo, E; De Capua, S; De Miranda, J M; De Paula, L; Del Buono, L; Dijkstra, H; Easo, S; Eidelman, S; Fu, J; Gallas Torreira, A; Gambetta, S; Gandini, P; Garcia Martin, L M; Grecu, A; Göbel, C; Heinicke, K; Henrard, P; Jones, C R; Klimkovich, T; Kucharczyk, M; Kuonen, A K; Kvaratskheliya, T; Lacarrere, D; Langenbruch, C; Latham, T; Li, Y; Li, Z; Lindner, R; Luppi, E; Lupton, O; Maciuc, F; Macko, V; Mackowiak, P; Majewski, M W; Marconi, U; Melnychuk, D; Merk, M; Morandin, M; Moron, J; Müller, D; Müller, J; Nasteva, I; Ossowska, A; Otalora Goicochea, J M; Oyanguren, A; Parker, W; Pellegrino, A; Penso, G; Polyakov, I; Popov, D; Potterat, C; Pullen, H; Quagliani, R; Rachwal, B; Rives Molina, V; Robbe, P; Romero Vidal, A; Ronayne, J W; Santamarina Rios, C; Schellenberg, M; Schiller, M; Schopper, A; Sestini, L; Shears, T; Smith, I T; Stefkova, S; Stone, S; Thomas, E; Tourinho Jadallah Aoude, R; Tully, A; Ukleja, A; Usachov, A; Vilasis-Cardona, X; Wallace, C; Walsh, J; Watson, N K; Whitehead, M; Williams, M P; Wraight, K; Xu, M; Zhang, Y
Physical review letters, 03/2018, Letnik: 120, Številka: 12Journal Article
A measurement is reported of the ratio of branching fractions R(J/ψ)=B(B_{c}^{+}→J/ψτ^{+}ν_{τ})/B(B_{c}^{+}→J/ψμ^{+}ν_{μ}), where the τ^{+} lepton is identified in the decay mode τ^{+}→μ^{+}ν_{μ}νover ¯_{τ}. This analysis uses a sample of proton-proton collision data corresponding to 3.0 fb^{-1} of integrated luminosity recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. A signal is found for the decay B_{c}^{+}→J/ψτ^{+}ν_{τ} at a significance of 3 standard deviations corrected for systematic uncertainty, and the ratio of the branching fractions is measured to be R(J/ψ)=0.71±0.17(stat)±0.18(syst). This result lies within 2 standard deviations above the range of central values currently predicted by the standard model.
