  Axion-Like-Particles are among the most economical and well motivated
extensions of the Standard Model. In this work ALP production from hadronic and
leptonic meson decays are studied. The hadronization part of these decay
amplitudes have been obtained using Brodsky-Lepage method or LQCD, at needs. In
particular, the general expressions for ALP emission in mesonic s- and
t-channel tree-level processes are thoroughly discussed, for pseudoscalar and
vector mesons. Accordingly, the calculation of the decay amplitudes for $M_I\to
M_F \,a$ and $M\to \ell \nu a$ are presented. Finally, bounds on the
(low-energy effective Lagrangian) ALP-fermion couplings are derived, from
present and future flavor experiments.
