Evidence for B − → D * * 0 τ − ν τ ¯ Decays

arXiv (Cornell University)

Abstract

The first evidence for the decay $B^-\rightarrow D^{**0}τ^-\overline{ν_τ}$ is obtained using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb$^{-1}$ , at centre-of-mass energies of 7, 8 and 13 Tev. Here, the $D^{**0}$ meson represents any of the three excited charm mesons $D_{1}(2420)^{0}$, $D_{2}^{*}(2460)^{0}$, and $D_{1}^{'}(2400)^{0}$. The $B^-\rightarrow D^{**0}τ^-\overline{ν_τ}$ signal is measured with a significance of 3.5 $σ$, including systematic uncertainties. The combined branching fraction $BR(B^-\rightarrow D^{**0}_{1,2}τ^-\overline{ν_τ})\times BR(D^{**0}_{1,2}\rightarrow D^{*+}π^-)$, where $D^{**0}_{1,2}$ denotes both $D_{1}(2420)^{0}$ and $D_{2}^{*}(2460)^{0}$ contributions, is measured to be $(0.051\pm0.013(stat)\pm 0.006(syst)\pm 0.009(\rm{ext}) )\%$, where the last uncertainty reflects that of the branching fraction of the normalisation channel $B^-\rightarrow D^{**0}_{1,2}D_s^{(*)-}$. The ratio between the tauonic and muonic semileptonic $B$ decays, with the latter taken from world average values, is also determined and found to be ${\cal R}(D^{**0}_{1,2})=0.13\pm0.03(stat)\pm0.01(syst)\pm0.02\,(\rm{ext})$.

Authors 30

1. R. Aaij
2. A. S. W. Abdelmotteleb
3. Carlos Abellán Beteta
4. F. Abudinén
5. T. Ackernley
6. A. A. Adefisoye
7. B. Adeva
8. M. Adinolfi
9. P. Adlarson
10. C. Agapopoulou

    Laboratoire de Physique des 2 Infinis Irène Joliot-Curie

    Affiliation as printed

    IJCLab - Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (Bât. 100 et 200, 15 rue Georges Clémenceau 91405 Orsay - France)

11. C. Aidala
12. Z. Ajaltouni

    Laboratoire de Physique de Clermont Auvergne

    Affiliation as printed

    LPC - Laboratoire de Physique de Clermont (Campus Universitaire des Cézeaux, 4 Avenue Blaise Pascal, TSA 60026, CS 6002, 63178 Aubière Cedex - France)

13. S. Akar
14. K. Carvalho Akiba
15. P. Albicocco
16. J. Albrecht
17. F. Alessio
18. R. Amalric
19. S. Amato

    Laboratoire de Physique Nucléaire et de Hautes Énergies

    Affiliation as printed

    LPNHE (UMR_7585) - Laboratoire de Physique Nucléaire et de Hautes Énergies (Barre 12-22, 1er étage 4 Place Jussieu 75252 Paris Cedex 05 - France)

20. J. M. Basels Aachen

    RWTH Aachen University

    Affiliation as printed

    RWTH Aachen

21. K. Belous
22. I. Belyaev
23. G. Bencivenni

    Centre de physique des particules de Marseille

    Affiliation as printed

    CPPM - Centre de Physique des Particules de Marseille (163, avenue de Luminy - Case 902 - 13288 Marseille cedex 09 - France)

24. E. Ben-Haim
25. Alexander Berezhnoy

    Laboratoire de Physique Nucléaire et de Hautes Énergies

    Affiliation as printed

    LPNHE (UMR_7585) - Laboratoire de Physique Nucléaire et de Hautes Énergies (Barre 12-22, 1er étage 4 Place Jussieu 75252 Paris Cedex 05 - France)

26. R. Bernet
27. P. Billoir
28. Alice Biolchini

    Laboratoire de Physique Nucléaire et de Hautes Énergies

    Affiliation as printed

    LPNHE (UMR_7585) - Laboratoire de Physique Nucléaire et de Hautes Énergies (Barre 12-22, 1er étage 4 Place Jussieu 75252 Paris Cedex 05 - France)

29. M. Birch
30. A. Bizzeti