General neutrino-scalar couplings appear in many extensions of Standard Model. We can probe these neutrino-scalar couplings by leptonic decay of mesons and from heavy neutrino search. Our analysis improves the present limits to $|g_e|^2<1.9\times 10^{ -6}$ and $|g_\mu|^2<1.9\times 10^{ -7}$ at 90\% C.L. for massless scalars. For massive scalars we found for the first time the constraints for $g^2_{ \alpha}$ couplings to be $10^{ -6}-10^{ -1}$ respectively for scalar masses between below 1 MeV and for 300 MeV.
Categories: hep-ph