Determination of Nucleon Form factors from Baryonic B Decays

It is the first time that the study of three-body baryonic B decays offers an independent determination of the nucleon form factors for the time-like four momentum transfer $(t>0)$ region, such as $G^{p,n}_M(t)$ of vector currents and those of axial ones. Explicitly, from the data of $\bar B^0\to n\bar p D^{*+}$ and $\Lambda\bar p\pi^+$ we find a constant ratio of $G^n_M(t)/G^p_M(t)=-1.3\pm0.4$, which supports the FENICE experimental result. The vector and axial-vector form factors of $p\bar n$, $p\bar p$ and $n\bar n$ pairs due to weak currents are also presented, which can be tested in future experiments.