Massive field contributions to the QCD vacuum tunneling amplitude - art. no. 114022

Far the one-loop contribution to the QCD vacuum tunneling amplitude by quar ks of generic mass value, we make use of a calculational scheme exploiting a large mass expansion together with a small mass expansion. The large mass expansion for the effective action is given by a series involving higher-o rder Seeley-DeWitt coefficients, and we carry this expansion up to order l/ (m rho)(8), where m denotes mass of the quark and rho the instanton size pa rameter. For the small mass expansion, we use the known exact expression fa r the particle propagation functions in an instanton background and evaluat e explicitly the effective action to order (m rho)(2) A smooth interpolatio n of the results from both expansions suggests that the quark contribution to the instanton tunneling amplitude have a relatively simple m rho -depend ent behavior.