Extrapolation and unitarity bounds for the $B\to \pi$ form factor

I. Sentitemsu Imsong, Alexander Khodjamirian, Thomas Mannel +1

We address the problem of extrapolating the vector form factor $f_{B\pi }^{+}$, which is relevant to $B\to \pi \ell {\nu }_{\ell }$ decays, from the region of small to the region of large momentum…