Abstract
A search is presented for axion-like particles (ALPs) with masses between 4.9 and 19.4 GeV decaying to a pair of photons, using proton-proton collisions collected with the LHCb detector during 2018 at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 2.1 fb−1. The same strategy and sample is used to search for the decays of the B0s, B0 and ηb mesons into photon pairs. No significant excess is found. Upper limits on the photon-pair branching fraction times the cross-section of ALP production are determined as a function of the ALP mass. Limits on the branching fractions of the beauty states are determined to be BR(B0s→γγ)<2.7×10−5, BR(B0→γγ)<0.83×10−5, and σ(pp→ηbX)×BR(ηb→γγ)<765pb at 95 % confidence level.
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