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 extract the dependence of hadronic form factors on q2 by varying the input heavy quark fragmentation function without the nearest pole dominance ansätze.
Study of Exclusive Charmless Semileptonic Decays of the B Meson