Reparametrization invariance and the expansion of currents in the heavy quark effective theory

The coefficients appearing at leading and subleading order in the 1/m expansion of bilinear heavy quark currents are related to each other by imposing reparametrization invariance on both the effective current operators and the short-distance coefficient functions in the heavy quark effective theory. When combined with present knowledge about the leading order coefficients, the results allow to calculate all coefficients appearing at order 1/m to next-to-leading order in renormalization-group improved perturbation theory. They also provide a meaningful definition of the velocity transfer variable v · v to order 1/m.