Lattice HQET Calculation of the Isgur-Wise Function

We calculate the Isgur-Wise function on the lattice, simulating the light quark with the Wilson action and the heavy quark with a direct lattice implementation of the heavy-quark effective theory. Improved smearing functions produced by a variational technique, MOST, are used to reduce the statistical errors and to minimize excited-state contamination of the ground-state signal. Calculating the required matching factors, we obtain $\xi'(1)=-0.64(13)$ for the slope of the Isgur-Wise function in continuum-HQET in the $\barMS$ scheme at a scale of $4.0 $GeV.