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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 | 2024/07 |
| 形態種別 | その他 |
| 標題 | Determination of $|V_{ub}|$ from simultaneous measurements of untagged $B^0\toπ^- \ell^+ ν_{\ell}$ and $B^+\toρ^0 \ell^+ν_{\ell}$ decays |
| 執筆形態 | その他 |
| 著者・共著者 | Belle II Collaboration,I. Adachi,L. Aggarwal,H. Aihara,N. Akopov,A. Aloisio,N. Althubiti,N. Anh Ky,D. M. Asner,H. Atmacan,T. Aushev,V. Aushev,M. Aversano,R. Ayad,V. Babu,H. Bae,S. Bahinipati,P. Bambade,Sw. Banerjee,S. Bansal,M. Barrett,J. Baudot,M. Bauer,A. Baur,A. Beaubien,F. Becherer,J. Becker,J. V. Bennett,F. U. Bernlochner,V. Bertacchi,M. Bertemes,E. Bertholet,M. Bessner,S. Bettarini,B. Bhuyan,F. Bianchi,L. Bierwirth,T. Bilka,D. Biswas,A. Bobrov,D. Bodrov,A. Bolz,J. Borah,A. Boschetti,A. Boz |
| 概要 | We present a measurement of $|V_{ub}|$ from a simultaneous study of the
charmless semileptonic decays $B^0\to\pi^- \ell^+ \nu_{\ell}$ and $B^+\to\rho^0 \ell^+\nu_{\ell}$, where $\ell = e, \mu$. This measurement uses a data sample of 387 million $B\overline{B}$ meson pairs recorded by the Belle~II detector at the SuperKEKB electron-positron collider between 2019 and 2022. The two decays are reconstructed without identifying the partner $B$ mesons. We simultaneously measure the differential branching fractions of $B^0\to\pi^- \ell^+ \nu_{\ell}$ and $B^+\to\rho^0 \ell^+\nu_{\ell}$ decays as functions of $q^2$ (momentum transfer squared). From these, we obtain total branching fractions $B(B^0\to\pi^- \ell^+ \nu_{\ell}) = (1.516 \pm 0.042 (\mathrm{stat}) \pm 0.059 (\mathrm{syst})) \times 10^{-4}$ and $B(B^+\to\rho^0 \ell^+\nu_{\ell}) = (1.625 \pm 0.079 (\mathrm{stat}) \pm 0.180 (\mathrm{syst})) \times 10^{-4}$. By fitting the measured $B^0\to\pi^- \ell^+ \nu_{\ell}$ partial branching fractions as functions of $q^2$, together with constraints on the non-perturbative hadronic contribution from lattice QCD calculations, we obtain $|V_{ub}|$ = $(3.93 \pm 0.09 \pm 0.13 \pm 0.19) \times 10^{-3}$. Here, the first uncertainty is statistical, the second is systematic, and the third is theoretical. |
| PermalinkURL | http://arxiv.org/abs/2407.17403v1 |
| researchmap用URL | http://arxiv.org/pdf/2407.17403v1 |