Light axion-like particles and the pseudoscalar mesonic decays M⃗M′νν¯

Abstract

The axion-like particle (ALP) is one kind of the best-motivated new particles. We consider its production from the pseudoscalar mesonic decays M→M′a , with M being a pseudoscalar meson B or K. The upper limits on the flavor-conserving ALP–quark coupling parameter g u are obtained by assuming the ALP to be an invisible particle. We find that the most severe constraint on g u comes from the decay K+→π+νν¯ for 0.05 GeV ≤ M a ≤ 0.35 GeV, while the decays B+,0→K+,0νν¯ and B+,0→π+,0νν¯ can also generate significant constraints.