Search for Axionlike Particles Produced in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math> Collisions at Belle II
F. Abudinén, I. Adachi, H. Aihara, Н. Акопов, A. Aloisio, F. Ameli, N. Anh Ky, D. M. Asner, T. Aushev, V. Aushev, V. Babu, S. Baehr, S. Bahinipati, P. Bambade, Sw. Banerjee, S. Bansal, J. Baudot, Jürgen Becker, P. K. Behera, J. V. Bennett, E. Bernieri, F. U. Bernlochner, M. Bertemes, M. Bessner, S. Bettarini, V. Bhardwaj, F. Bianchi, T. Bilka, S. Bilokin, D. Biswas, M. Bračko, P. Branchini, N. Braun, T. E. Browder, A. Budano, S. Bussino, M. Campajola, G. Casarosa, C. Cecchi, D. Červenkov, M.-C. Chang, P. Chang, R. Cheaib, V. Chekelian, B. G. Cheon, K. Chilikin, K. Chirapatpimol, H.-E. Cho, K. Cho, S.-J. Cho, S.-K. Choi, D. Cinabro, L. Corona, L. Cremaldi, S. Cunliffe, N. Dash, F. Dattola, E. De La Cruz–Burelo, G. De Nardo, M. De Nuccio, G. De Pietro, R. de Sangro, M. Destefanis, A. De Yta-Hernandez, F. Di Capua, Z. Doležal, T. V. Dong, K. Dort, D. Dossett, G. Dujany, S. Eidelman, T. Ferber, D. Ferlewicz, S. Fiore, A. Fodor, F. Forti, B. G. Fulsom, E. Ganiev, R. B. Garg, A. Garmash, V. Gaur, A. Gaz, U. Gebauer, A. Gellrich, Thomas Geßler, R. Giordano, A. Giri, B. Gobbo, R. Godang, P. Goldenzweig, B. Golob, P. Gomis, W. Gradl, E. Graziani, D. Greenwald, C. Hadjivasiliou, S. Halder, O. Hartbrich, K. Hayasaka, H. Hayashii
Abstract
We present a search for the direct production of a light pseudoscalar $a$ decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\gamma}a$, $a\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ in the mass range $0.2<{m}_{a}<9.7\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ using data corresponding to an integrated luminosity of $(445\ifmmode\pm\else\textpm\fi{}3)\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$ of ALPs to photons at the level of ${10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$. The limits are the most restrictive to date for $0.2<{m}_{a}<1\text{ }\text{ }\mathrm{GeV}/{c}^{2}$.