Light axion-like particles and the pseudoscalar mesonic decays M ⃗ M ′ ν ν ¯

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 + ν ν ¯ for 0.05 GeV ≤ M a ≤ 0.35 GeV, while the decays B + , 0 → K + , 0 ν ν ¯ and B + , 0 → π + , 0 ν ν ¯ can also generate significant constraints.