Chiral dynamics and S-wave contributions in ${\bar{B}}^0/D^0\to {\pi }^{\pm }\eta l^{\mp }\nu$ decays

Abstract

In this work, we analyze the semi-leptonic decays ${\bar{B}}^0/D^0\to (a_0(980{)}^{\pm }\to {\pi }^{\pm }\eta )l^{\mp }\nu$ 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 $\pi \eta$ 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 ${\bar{B}}^0$ decay can be tested in future experiments.

Comments: 19 pages, 5 figures