Chiral dynamics and S-wave contributions in $\bar B^0/D^0 \to π^{\pm}η l^{\mp} ν$ decays

Abstract

In this work, we analyze the semi-leptonic decays B0 /D 0 → (a 0 (980) ± → π ± η)l ∓ ν within light-cone sum rules. The two and three-body light-cone distribution amplitudes (LCDAs) of the B meson and the only available two-body LCDA of the D meson are used. To include the finite-width effect of the a 0 (980), we use a scalar form factor to describe the final-state interaction between the πη mesons, which was previously calculated within unitarized Chiral Perturbation Theory. The result for the decay branching fraction of the D 0 decay is in good agreement with that measured by the BESIII Collaboration, while the branching fraction of the B0 decay can be tested in future experiments.