  We analyze, in a fully model-independent manner, the effects of new physics
on a few semi-hadronic three-body meson decays of the type $P_i \to P_f f_1
f_2$, where $P_i$, $P_f$ are well chosen pseudo-scalar mesons and $f_{1,2}$
denote fermions out of which at least one gets detected in experiments. We find
that the angular distribution of events of these decays can probe many
interesting new physics, such as the nature of the intermediate particle that
can cause lepton-flavor violation, or presence of heavy sterile neutrino, or
new intermediate particles, or new interactions. We also provide angular
asymmetries which can quantify the effects of new physics in these decays. We
illustrate the effectiveness of our proposed methodology with a few well chosen
decay modes showing effects of certain new physics possibilities without any
hadronic uncertainties.
