Observation of two new Ξ(b)(-) baryon resonances

• Published in: Physical review letters 2015-02, Vol.114 (6), p.062004-062004
• Main Authors: Aaij, R, Adeva, B, Adinolfi, M, Affolder, A, Ajaltouni, Z, Akar, S, Albrecht, J, Alessio, F, Alexander, M, Ali, S, Alkhazov, G, Alvarez Cartelle, P, Alves, Jr, A A, Amato, S, Amerio, S, Amhis, Y, An, L, Anderlini, L, Anderson, J, Andreassen, R, Andreotti, M, Andrews, J E, Appleby, R B, Aquines Gutierrez, O, Archilli, F, Artamonov, A, Artuso, M, Aslanides, E, Auriemma, G, Baalouch, M, Bachmann, S, Back, J J, Badalov, A, Baesso, C, Baldini, W, Barlow, R J, Barschel, C, Barsuk, S, Barter, W, Batozskaya, V, Battista, V, Bay, A, Beaucourt, L, Beddow, J, Bedeschi, F, Bediaga, I, Belogurov, S, Belous, K, Belyaev, I, Ben-Haim, E, Bencivenni, G, Benson, S, Benton, J, Berezhnoy, A, Bernet, R, Bertolin, A, Bettler, M-O, van Beuzekom, M, Bien, A, Bifani, S, Bird, T, Bizzeti, A, Bjørnstad, P M, Blake, T, Blanc, F, Blouw, J, Blusk, S, Bocci, V, Bondar, A, Bondar, N, Bonivento, W, Borghi, S, Borgia, A, Borsato, M, Bowcock, T J V, Bowen, E, Bozzi, C, Brett, D, Britsch, M, Britton, T, Brodzicka, J, Brook, N H, Bursche, A, Buytaert, J, Cadeddu, S, Calabrese, R, Calvi, M, Calvo Gomez, M, Campana, P, Campora Perez, D, Capriotti, L, Carbone, A, Carboni, G, Cardinale, R, Cardini, A, Carson, L, Carvalho Akiba, K, Casanova Mohr, R C M, Casse, G, Cassina, L
• Format: Article
• Language: English
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.114.062004

Two structures are observed close to the kinematic threshold in the Ξ(b)(0)π(-) mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0  fb(-1), recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity J(P)=(1/2)(+) and J(P)=(3/2)(+) states, denoted Ξ(b)('-) and Ξ(b)(*-). Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ(b)('-))-m(Ξ(b)(0))-m(π(-))=3.653±0.018±0.006  MeV/c(2), m(Ξ(b)(*-))-m(Ξ(b)(0))-m(π(-))=23.96±0.12±0.06  MeV/c(2), Γ(Ξ(b)(*-))=1.65±0.31±0.10  MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξ(b)('-))