Light quark dependence of the Isgur-Wise function from QCD sum rules.

We study light quark dependence of the Isgur-Wise function for Ba → Da and Ba → D∗ a in the framework of QCD sum rules. At zero recoil , all the Isgur-Wise functions equal as required by heavy quark symmetry and at non-zero recoil, the Isgur-Wise function for Bs decay falls faster than that for Bu,d decay , which is just contrary to the recent prediction of the heavy meson chiral perturbation theory. As by-products, we also estimate SU(3) breaking effects in the mass and the decay constant. PACS number(s): 11.50.Li,12.38.Cy,12.38.Lg,13.25.+m This project was supported by the National Science Foundation of China and the Grant LWTZ1298 of the Chinese Academy of Science. Mailing address