The Isgur-Wise function on the lattice

The h+, h_A1 form factors for the semi-leptonic B->D and B->D* decays are evaluated in quenched lattice QCD with beta=6.2. The action and the operators are fully O(a) non-perturbatively improved. The Isgur-Wise function is evaluated and fitted to extract its slope; the latter is found to be rho^2=1.1(2)(3) from the B->D* decay and rho^2=1.0(2)(3) from the B->D decay. The form factors ratios R_1, R_2 are evaluated and found to be in agreement with experimental determinations.