Form Factors for Exclusive Semileptonic $B$--Decays

Abstract

We developed the new parton model approach for exclusive semileptonic decays of $B$-meson to $D,D^{\ast }$ by extending the inclusive parton model, and by combining with the results of the HQET, motivated by Drell-Yan process. Without the nearest pole dominance ansätze, we {\bf derived} the dependences of hadronic form factors on $q^2$. We also calculated numerically the slope of the Isgur-Wise function, which is consistent with the experimental results.

20 pages, RevTex, 2 ps figure files(uuencoded in seperate file)