Width difference in the Bs system from lattice HQET

We present recent results for the prediction of the Bs lifetime difference from lattice Heavy Quark Effective Theory simulations. In order to get a next-to-leading order result we have calculated the matching between QCD and HQET and the two loop anomalous dimension in the HQET for all the \Delta B=2 operators, in particular for the operators which enter in the width difference. We obtain for the Bs lifetime difference, (\Delta\Gamma_Bs/\Gamma_Bs)=(5.1+/- 1.9+/- 1.7)10^(-2).