Search for axion-like particles produced in $e^+e^{\mathstrut -}$ collisions at Belle II

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 ${e^+e^-\to\gamma a, a \to\gamma\gamma}$ in the mass range ${0.2} \,< m_a < {9.7}\,{\text{GeV/$c$}^2}$ using data corresponding to an integrated luminosity of $(445\pm 3)\,\text{pb}^{-1}$. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axion-like 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 $g_{a\gamma\gamma}$ of ALPs to photons at the level of $10^{-3}\,{\text{GeV}^{-1}}$. The limits are the most restrictive to date for $0.2\,<\,m_a\,<\,1\,{\text{GeV/$c$}^2}$.
Tags
Working group Dark Sector and Low Multiplicity
Principal authors @  Michael De Nuccio, Torben Ferber
Reference Phys.Rev.Lett. 125, 161806 (2020), DOI: 10.1103/PhysRevLett.125.161806
Document BELLE2-PUB-PH-2020-001
Links arXiv:2007.13071, Inspire, PRL
Bibtex 
@article{Belle-II:2020jti,
    author = "Abudin{\'e}n, F. and others",
    collaboration = "Belle-II",
    title = "{Search for Axion-Like Particles produced in $e^+e^-$ collisions at Belle II}",
    eprint = "2007.13071",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2020-001, KEK Preprint 2020-10",
    doi = "10.1103/PhysRevLett.125.161806",
    journal = "Phys. Rev. Lett.",
    volume = "125",
    number = "16",
    pages = "161806",
    year = "2020"
}