Effect of m(c) on b quark chromomagnetic interaction and on-shell two-loopintegrals with two masses - art. no. 054023

The effect of a nonzero c quark mass on the b quark HQET Lagrangian, up to the 1/m(b) level, is calculated at two loops. The results are expressed in terms of dilogarithmic functions of m(c)/m(b). This calculation involves on -shell two-loop propagator-type diagrams with two different masses m(b) and m(c). A general algorithm for reducing such Feynman integrals to the basis of two nontrivial and two trivial integrals is constructed. [S0556-2821(99 )05403-X].