Study of charmonium production in b -hadron decays and first evidence for the decay Bs0

R. Aaij, B. Adeva, Z. Ajaltouni, S. Akar, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, L. An, L. Anderlini, G. Andreassi, M. Andreotti, J. E. Andrews, R. B. Appleby, F. ArchilliP. d’Argent, J. Arnau Romeu, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, M. Baalouch, I. Babuschkin, S. Bachmann, J. J. Back, A. Badalov, C. Baesso, S. Baker, K. Carvalho Akiba, V. Coco, K. De Bruyn, M. Ferro-Luzzi, T. Ketel, J. van Leerdam, M. Merk, C. J.G. Onderwater, G. Raven, M. Schiller, N. Serra, B. Storaci, V. Syropoulos, J. van Tilburg, S. Tolk, P. Tsopelas, N. Tuning, LHCb Collaboration

Research output: Contribution to JournalArticleAcademicpeer-review


Using decays to ϕ-meson pairs, the inclusive production of charmonium states in b-hadron decays is studied with pp collision data corresponding to an integrated luminosity of 3.0fb-1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by BC≡B(b→CX)×B(C) the inclusive branching fraction of a b hadron to a charmonium state C that decays into a pair of ϕ mesons, ratios RC2C1≡BC1/BC2 are determined as Rηc(1S)χc0=0.147±0.023±0.011, Rηc(1S)χc1=0.073±0.016±0.006, Rηc(1S)χc2=0.081±0.013±0.005, Rχc0χc1=0.50±0.11±0.01, Rχc0χc2=0.56±0.10±0.01 and Rηc(1S)ηc(2S)=0.040±0.011±0.004. Here and below the first uncertainties are statistical and the second systematic. Upper limits at 90% confidence level for the inclusive production of X(3872), X(3915) and χ c 2(2 P) states are obtained as Rχc1X(3872)<0.34, Rχc0X(3915)<0.12 and Rχc2χc2(2P)<0.16. Differential cross-sections as a function of transverse momentum are measured for the ηc(1 S) and χc states. The branching fraction of the decay Bs0 is measured for the first time, B(Bs0)=(2.15±0.54±0.28±0.21B)×10-6. Here the third uncertainty is due to the branching fraction of the decay Bs0, which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse ϕ polarization is observed. The measurements allow the determination of the ratio of the branching fractions for the ηc(1 S) decays to ϕϕ and pp¯ as B(ηc(1S))/B(ηc(1S)→pp¯)=1.79±0.14±0.32.

Original languageEnglish
Article number609
JournalEuropean Physical Journal C
Issue number9
Publication statusPublished - 1 Sep 2017

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