We investigate the form factors for exclusive semileptonic decays of $B$-meson to $D,~D^*$, based on the parton picture and helped by the results of the HQET. We obtain the numerical results for the slope of the Isgur-Wise function, which is consistent with the experimental results, and we extracte the dependences of hadronic form factors on $q^2$ by varying input heavy quark fragmentation function without the nearest pole dominance ans\"atze.
Categories: hep-ph