On the chromomagnetic expectation value μG2 and higher power corrections in heavy flavor mesons

The important parameter mu(G)(2) of the heavy quark expansion is analyzed including perturbative and power corrections. The former are found small; a nonperturbative relation is suggested which allows to control power corrections. We conclude that mu(G)(2) (1 GeV) = 0.35(-0.02)(+0.03) GeV2. The effective coupling alpha(s)((me)) (omega) governing the normalization scale evolution of mu(G)(2) is given to two loops. On the nonperturbative side, we advocate the utility of combining the heavy quark expansion with expanding around the BPS-type approximation for the meson wavefunction, which implies relations mu(pi)(2) approximate to mu(G)(2), - -rho(LS)(3) approximate to rho(D)(3) and similar ones for the nonlocal correlators. (C) 2002 Elsevier Science B.V All rights reserved.