FIRST LATTICE CALCULATION OF THE B-MESON BINDING AND KINETIC ENERGIES

We present the first lattice calculation of the B-meson binding energy <(Lambda)over bar> and of the kinetic energy -lambda(1)/2m(Q) of the heavy-quark inside the pseudoscalar B-meson. This calculation has requ ired the non-perturbative subtraction of the power divergences present in matrix elements of the Lagrangian operator <(h)over bar D(4)h> and of the kinetic energy operator <(h)over bar D(2)h>, The non-perturbat ive renormalisation of the relevant operators has been implemented by imposing suitable renormalisation conditions on quark matrix elements, in the Landau gauge. Our numerical results have been obtained from se veral independent numerical simulations at beta = 6.0 and 6.2, and usi ng, for the meson correlators, the results obtained by the APE group a t the same values of beta. Our best estimate, obtained by combining re sults at different values of beta, is <(Lambda)over bar> = 190(-30)(+5 0) MeV. For the <(MS)over bar> running mass, we obtain <(m)over bar (b )> (<(m)over bar (b)>) = 4.17 +/- 0.06 GeV, in reasonable agreement wi th previous determinations. From a subset of 36 configurations, we wer e only able to establish a loose upper bound on the 6-quark kinetic en ergy in a B-meson, lambda(1) = [B\<(h)over bar D(2)h>\B]/(2M(B)) < 1 G eV2. This shows that a much larger statistical sample is needed to det ermine this important parameter.