Light quark dependence of the Isgur-Wise function

Heavy quark spin flavor symmetry allows the form factors of B→D and B→D* semileptonic decay to be written in terms of a single universal function, the Isgur-Wise function. In the SU(3)V limit, the Isgur-Wise function is independent of light quark flavor. Leading SU(3)V violating corrections to the ratio of Isgur-Wise functions for BS versus B decay are computed in chiral perturbation theory. The correction is velocity dependent, but vanishes at zero recoil as required by heavy quark symmetry. (orig.)