Evidence for Exotic Hadron Contributions to Λb0 →j /ψpπ- Decays

Author(s): Aaij, R; Abellan Beteta, C; Adeva, B; Adinolfi, M; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, AA; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Andreassi, G; Andreotti, M; Andrews, JE; Appleby, RB; Aquines Gutierrez, O; Archilli, F; D'Argent, P; Arnau Romeu, J; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Bachmann, S; Back, JJ; Badalov, A; Baesso, C; Baldini, W; Barlow, RJ; Barschel, C; Barsuk, S; Barter, W; Batozskaya, V; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Bel, LJ; Bellee, V; Belloli, N; Belous, K; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Benton, J; Berezhnoy, A; Bernet, R; Bertolin, A; Bettler, MO; Van Beuzekom, M; Bifani, S; Billoir, P; Bird, T; Birnkraut, A; Bitadze, A; Bizzeti, A; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Boettcher, T; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borisyak, M; Borsato, M; Bossu, F; Boubdir, M; Bowcock, TJV; Bowen, E; Bozzi, C; Braun, S | Abstract: © 2016 CERN. A full amplitude analysis of Λb0→J/ψpπ- decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb-1. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ-, either the Pc(4380)+ and Pc(4450)+→J/ψp states, previously observed in Λb0→J/ψpK- decays, or the Zc(4200)-→J/ψπ- state, previously reported in B0→J/ψK+π- decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the Pc(4380)+ and Pc(4450)+ production rates expected from their previous observation taking account of Cabibbo suppression.