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arXiv · 2111.00710

Exclusive $B \to X_u \ell \nu_\ell$ Decays with Hadronic Full-event-interpretation Tagging in 62.8 fb$^{-1}$ of Belle II Data

Belle II Collaboration·F. Abudinén·I. Adachi·R. Adak·K. Adamczyk·L. Aggarwal·P. Ahlburg·H. Ahmed·J. K. Ahn·H. Aihara·N. Akopov·A. Aloisio·F. Ameli·L. Andricek·N. Anh Ky·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·V. Aushev·T. Aziz·V. Babu·S. Bacher·H. Bae·S. Baehr·S. Bahinipati·A. M. Bakich·P. Bambade·Sw. Banerjee·S. Bansal·M. Barrett·G. Batignani·J. Baudot·M. Bauer·A. Baur·A. Beaulieu·J. Becker·P. K. Behera·J. V. Bennett·E. Bernieri·F. U. Bernlochner·M. Bertemes·E. Bertholet·M. Bessner·S. Bettarini·V. Bhardwaj·B. Bhuyan·F. Bianchi·T. Bilka·S. Bilokin·D. Biswas·A. Bobrov·D. Bobrov·A. Bolz·A. Bondar·G. Bonvicini·A. Bozek·M. Bračko·P. Branchini·N. Braun·R. A. Briere·T. E. Browder·D. N. Brown·A. Budano·L. Burmistrov·S. Bussino·M. Campajola·L. Cao·G. Caria·G. Casarosa·C. Cecchi·D. Červenkov·M. -C. Chang·P. Chang·R. Cheaib·V. Chekelian·C. Chen·Y. Q. Chen·Y. -T. Chen·B. G. Cheon·K. Chilikin·K. Chirapatpimol·H. -E. Cho·K. Cho·S. -J. Cho·S. -K. Choi·S. Choudhury·D. Cinabro·L. Corona·L. M. Cremaldi·D. Cuesta·S. Cunliffe·T. Czank·N. Dash·F. Dattola·E. De La Cruz-Burelo·G. de Marino·G. De Nardo·M. De Nuccio·G. De Pietro
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Abstract

We present a reconstruction in early data of the semileptonic decay $B^+ \to \pi^0 \ell^+ \nu_\ell$, and first results of a reconstruction of the decays $B^+ \to \rho^0 \ell^+ \nu_\ell$ and $B^0 \to \rho^- \ell^+ \nu_\ell$ in a sample corresponding to 62.8 fb$^{-1}$ of Belle II data using hadronic $B$-tagging via the full-event-interpretation algorithm. We determine the total branching fractions via fits to the distribution of the square of the missing mass, and find $\mathcal{B}(B^+ \to \pi^0 \ell^+ \nu_\ell)$ = (8.29 $\pm$ 1.99(stat) $\pm$ 0.46(syst)) $\times 10^{-5}$. We obtain $95\%$ CL upper limits on the branching fractions with $\mathcal{B}(B^0 \to \rho^- \ell^+ \nu_\ell) < 3.37 \times 10^{-4}$ and $\mathcal{B}(B^+ \to \rho^0 \ell^+ \nu_\ell) < 19.7 \times 10^{-5}$. We also obtain an updated branching fraction for the $B^0 \to \pi^- \ell^+ \nu_\ell$ decay, $\mathcal{B}(B^0 \to \pi^- \ell^+ \nu_\ell)$ = (1.47 $\pm$ 0.29(stat) $\pm$ 0.05(syst)) $\times 10^{-4}$, based on the sum of the partial branching fractions in three bins of the squared momentum transfer to the leptonic system.

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Belle II Collaboration, F. Abudinén, I. Adachi, R. Adak, K. Adamczyk, L. Aggarwal, P. Ahlburg, H. Ahmed, J. K. Ahn, H. Aihara, N. Akopov, A. Aloisio, F. Ameli, L. Andricek, N. Anh Ky, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, V. Aushev, T. Aziz, V. Babu, S. Bacher, H. Bae, S. Baehr, S. Bahinipati, A. M. Bakich, P. Bambade, Sw. Banerjee, S. Bansal, M. Barrett, G. Batignani, J. Baudot, M. Bauer, A. Baur, A. Beaulieu, J. Becker, P. K. Behera, J. V. Bennett, E. Bernieri, F. U. Bernlochner, M. Bertemes, E. Bertholet, M. Bessner, S. Bettarini, V. Bhardwaj, B. Bhuyan, F. Bianchi, T. Bilka, S. Bilokin, D. Biswas, A. Bobrov, D. Bobrov, A. Bolz, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, P. Branchini, N. Braun, R. A. Briere, T. E. Browder, D. N. Brown, A. Budano, L. Burmistrov, S. Bussino, M. Campajola, L. Cao, G. Caria, G. Casarosa, C. Cecchi, D. Červenkov, M. -C. Chang, P. Chang, R. Cheaib, V. Chekelian, C. Chen, Y. Q. Chen, Y. -T. Chen, B. G. Cheon, K. Chilikin, K. Chirapatpimol, H. -E. Cho, K. Cho, S. -J. Cho, S. -K. Choi, S. Choudhury, D. Cinabro, L. Corona, L. M. Cremaldi, D. Cuesta, S. Cunliffe, T. Czank, N. Dash, F. Dattola, E. De La Cruz-Burelo, G. de Marino, G. De Nardo, M. De Nuccio, G. De Pietro. 2021-11-01. Exclusive $B \to X_u \ell \nu_\ell$ Decays with Hadronic Full-event-interpretation Tagging in 62.8 fb$^{-1}$ of Belle II Data. https://arxiv.org/abs/2111.00710

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