  The worldline variational approach is extended beyond the quenched
approximation, i.e. to include virtual pair production of heavy particles. This
is achieved either by an expansion of the functional determinant to second
order or by an hybrid ansatz for the quadratic trial action consisting of
fields for the light particles and worldlines for the heavy ones as in the
linear polaron model. Numerical results and analytic approximations show a
reduction of radiative effects with increasing number of flavors.
