The B -> D* l nu Form Factor at Zero Recoil

Abstract

We describe a model independent lattice QCD method for determining the deviation from unity for h_{A1}(1), the B -> D* l nu form factor at zero recoil. We extend the double ratio method previously used to determine the B -> D l nu form factor. The bulk of statistical and systematic errors cancel in the double ratios we consider, yielding form factors which promise to reduce present theoretical uncertainties in the determination of V_{cb}. We present results from a prototype calculation at a single lattice spacing corresponding to beta=5.7.

Comments: Lattice99(heavyquarks); 3 pgs, LaTeX