Light axion-like particles and the pseudoscalar mesonic decays M→M′νν

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+->pi(+)nu nu for 0.05 GeV <= M-a <= 0.35 GeV, while the decays B-+,B-0 -> K-+,K-0 nu nu and B-+,B-0 ->pi(+,0)nu nu can also generate significant constraints.