b quark kinetic energy in the Λb

We consider the problem of determining the matrix element of the heavy quark kinetic energy operator K between Λb baryonic states by three-point function QCD sum rules in the heavy quark effective theory. We discuss the main features and the uncertainties associated with such an approach. Numerically, we find the result left-angle K right-angle Λb≅-0.6 GeV2, qualitatively similar to the analogous quantity left-angle K right-angle Bd. copyright 1996 The American Physical Society