Determination of the strong coupling $g_{B^{\ast }B\pi }$ from semi-leptonic $B\to \pi \ell \nu$ decay

Xin-Qiang Li, Fang Su, Ya-Dong Yang

According to heavy-meson chiral perturbation theory, the vector form factor $f_{+}(q^2)$ of exclusive semi-leptonic decay $B\to \pi \ell \nu$ is closely related, at least in the soft-pion…