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新山 雅之 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 発行・発表の年月 | 2016/12 |
| 形態種別 | その他 |
| 標題 | Measurement of the $τ$ lepton polarization and $R(D^*)$ in the decay $\bar{B} \to D^* τ^- \barν_τ$ |
| 執筆形態 | その他 |
| 著者・共著者 | S. Hirose,T. Iijima,I. Adachi,K. Adamczyk,H. Aihara,S. Al Said,D. M. Asner,H. Atmacan,V. Aulchenko,T. Aushev,R. Ayad,V. Babu,I. Badhrees,A. M. Bakich,V. Bansal,E. Barberio,P. Behera,M. Berger,B. Bhuyan,J. Biswal,A. Bondar,G. Bonvicini,A. Bozek,M. Bračko,T. E. Browder,D. Červenkov,P. Chang,A. Chen,B. G. Cheon,K. Chilikin,R. Chistov,K. Cho,Y. Choi,D. Cinabro,M. Danilov,N. Dash,S. Di Carlo,J. Dingfelder,Z. Doležal,Z. Drásal,D. Dutta,S. Eidelman,D. Epifanov,H. Farhat,J. E. Fast,T. Ferber,B. G. Fulso |
| 概要 | We report the first measurement of the $\tau$ lepton polarization
$P_\tau(D^*)$ in the decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = \mathcal{B}(\bar {B} \rightarrow D^* \tau^- \bar{\nu}_\tau) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \bar{\nu}_\ell)$, where $\ell^-$ denotes an electron or a muon, and the $\tau$ is reconstructed in the modes $\tau^- \rightarrow \pi^- \nu_\tau$ and $\tau^- \rightarrow \rho^- \nu_\tau$. We use the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our results, $P_\tau(D^*) = -0.38 \pm 0.51 {\rm (stat.)} ^{+0.21}_{-0.16} {\rm (syst.)}$ and $R(D^*) = 0.270 \pm 0.035{\rm (stat.)} ^{+0.028}_{-0.025}{\rm (syst.)}$, are consistent with the theoretical predictions of the Standard Model. |
| DOI | 10.1103/PhysRevLett.118.211801 |
| PermalinkURL | http://arxiv.org/abs/1612.00529v2 |
| researchmap用URL | http://arxiv.org/pdf/1612.00529v2 |