Search for an axion-like particle in B → K(*)a(→ γγ) decays at Belle

Abstract

We report a search for an axion-like particle a in B → K(*)a decays using data collected with the Belle detector at the KEKB asymmetric-energy electron-positron collider. The search is based on a 711 fb−1 data sample collected at the Υ(4S) resonance energy, corresponding to a sample of 772 × 106 Υ(4S) events. In this study, we search for the decay of the axion-like particle into a pair of photons, a → γγ. We scan the two-photon invariant mass in the range 0.16 GeV–4.50 GeV for the K modes and 0.16 GeV–4.20 GeV for the K* modes. No significant signal is observed in any of the modes, and 90% confidence level upper limits are established on the coupling to the W boson, gaW, as a function of a m..