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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+eγa, aγγ in the mass range 0.2 < ma < 9.7 GeV/c2 using data corresponding to an integrated luminosity of (445± 3) pb−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 gaγγ of ALPs to photons at the level of 10−3 GeV−1. The limits are the most restrictive to date for 0.2< ma < 1 GeV/c2 .

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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

APA Citation

Abudinén, F., Adachi, I., Aihara, H., Akopov, N., Aloisio, A., Ameli, F., Anh Ky, N., Asner, D. M., Aushev, T., Aushev, V., Babu, V., Baehr, S., Bahinipati, S., Bambade, P., Banerjee, Sw., Bansal, S., Baudot, J., Becker, J., Behera, P. K., … Zhukova, V. I. (2020). Search for Axionlike particles produced in . Physical Review Letters, 125(16).

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