
We use a method recently suggested for evaluating the slope of the IsgurWise function, at the zerorecoil point, on the lattice. The computations are performed in the quenched approximation to lattice QCD, on a 24(3) x 48 lattice at beta = 6.2, using an O(a)improved action for the fermions. We have found unexpectedly large finitevolume effects in such a calculation. These volume corrections turned out to be purely geometrical and independent of the dynamics of the system. After the study of these effects on a smaller volume and for different quark masses, we give approximate expressions that account for them. Using these approximations we find xi'(1) = 1.7 (+2)(2) and xi'(1) = 1.4 (+2)(1) for the slope of the IsgurWise function, for two mesons composed of a heavy quark slightly heavier and lighter, respectively, than the charm quark, and in both cases, a light antiquark whose mass is about that of the strange quark.


Lellouch, Laurent Nieves Pamplona, Juan Miguel Sachrajda, Christopher T. Stella, N. Wittig, Hartmut Martinelli, Guido Richards, D.G. 1995 Geometrical volume effects in the computation of the slope of the isgurwise function Nuclear Physics B 444 12 401 424 