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arXiv · 2405.19734

Search for the decay $B^{0}\to\gamma\gamma$ using Belle and Belle II data

Belle·Belle II Collaborations·:·I. Adachi·L. Aggarwal·H. Aihara·N. Akopov·A. Aloisio·S. Al Said·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·A. Baur·A. Beaubien·F. Becherer·J. Becker·K. Belous·J. V. Bennett·F. U. Bernlochner·V. Bertacchi·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. Bozek·M. Bračko·P. Branchini·R. A. Briere·T. E. Browder·A. Budano·S. Bussino·Q. Campagna·M. Campajola·L. Cao·G. Casarosa·C. Cecchi·J. Cerasxoli·M. -C. Chang·P. Chang·P. Cheema·C. Chen·B. G. Cheon·K. Chilikin·K. Chirapatpimol·H. -E. Cho·K. Cho·S. -J. Cho·S. -K. Choi·S. Choudhury·L. Corona·J. X. Cui·F. Dattola·E. De La Cruz-Burelo·S. A. De La Motte·G. De Nardo·M. De Nuccio·G. De Pietro·R. de Sangro·M. Destefanis·S. Dey·R. Dhamija·A. Di Canto·F. Di Capua·J. Dingfelder·Z. Doležal·I. Domínguez Jiménez·T. V. Dong·M. Dorigo·D. Dorner·K. Dort·D. Dossett·S. Dreyer·S. Dubey·K. Dugic·G. Dujany·P. Ecker·M. Eliachevitch·D. Epifanov
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Abstract

We report the result of a search for the rare decay $B^{0} \to \gamma \gamma$ using a combined dataset of $753\times10^{6}$ $B\bar{B}$ pairs collected by the Belle experiment and $387\times10^{6}$ $B\bar{B}$ pairs collected by the Belle II experiment from decays of the $\rm \Upsilon(4S)$ resonance produced in $e^{+}e^{-}$ collisions. A simultaneous fit to the Belle and Belle II data sets yields $11.0^{+6.5}_{-5.5}$ signal events, corresponding to a 2.5$\sigma$ significance. We determine the branching fraction $\mathcal{B}(B^{0} \to \gamma\gamma) = (3.7^{+2.2}_{-1.8}(\rm stat)\pm0.5(\rm syst))\times10^{-8}$ and set a 90% credibility level upper limit of $\mathcal{B}(B^{0} \to \gamma\gamma) < 6.4\times10^{-8}$.

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Belle, Belle II Collaborations, :, I. Adachi, L. Aggarwal, H. Aihara, N. Akopov, A. Aloisio, S. Al Said, 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, A. Baur, A. Beaubien, F. Becherer, J. Becker, K. Belous, J. V. Bennett, F. U. Bernlochner, V. Bertacchi, 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. Bozek, M. Bračko, P. Branchini, R. A. Briere, T. E. Browder, A. Budano, S. Bussino, Q. Campagna, M. Campajola, L. Cao, G. Casarosa, C. Cecchi, J. Cerasxoli, M. -C. Chang, P. Chang, P. Cheema, C. Chen, B. G. Cheon, K. Chilikin, K. Chirapatpimol, H. -E. Cho, K. Cho, S. -J. Cho, S. -K. Choi, S. Choudhury, L. Corona, J. X. Cui, F. Dattola, E. De La Cruz-Burelo, S. A. De La Motte, G. De Nardo, M. De Nuccio, G. De Pietro, R. de Sangro, M. Destefanis, S. Dey, R. Dhamija, A. Di Canto, F. Di Capua, J. Dingfelder, Z. Doležal, I. Domínguez Jiménez, T. V. Dong, M. Dorigo, D. Dorner, K. Dort, D. Dossett, S. Dreyer, S. Dubey, K. Dugic, G. Dujany, P. Ecker, M. Eliachevitch, D. Epifanov. 2024-05-30. Search for the decay $B^{0}\to\gamma\gamma$ using Belle and Belle II data. https://doi.org/10.1103/physrevd.110.l031106

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