  Although one-loop calculations provide a realistic description of bulk and
single-particle nuclear properties, it is necessary to examine loop corrections
to develop a systematic finite-density power-counting scheme for the nuclear
many-body problem when loops are included. Moreover, it is imperative to study
exchange and correlation corrections systematically to make reliable
predictions for other nuclear observables. One must also verify that the
natural sizes of the one-loop parameters are not destroyed by explicit
inclusion of many-body corrections. The loop expansion is applied to a chiral
effective hadronic lagrangian; with the techniques of Infrared Regularization,
it is possible to separate out the short-range contributions and to write them
as local products of fields that are already present in our lagrangian. (The
appropriate field variables must be re-defined at each order in loops.) The
corresponding parameters implicitly include short-range effects to all orders
in the interaction, so these effects need not be calculated explicitly. The
remaining (long-range) contributions that must be calculated are nonlocal and
resemble those in conventional nuclear-structure calculations. Calculations at
the two-loop level are carried out to illustrate these techniques at finite
densities and to verify that the coupling parameters remain natural when fitted
to the empirical properties of equilibrium nuclear matter.
