Renormalization-group improved effective Lagrangian for interacting theories in curved spacetime

A method for finding the renormalization group (RG) improved effective Lagrangian for a massive interacting field theory in curved spacetime is presented. As a particular example, the λφ-theory is considered and the RG improved effective Lagrangian is explicitly found up to second order in the curvature tensors. As a further application, the curvature-induced phase transitions are discussed for both the massive and the massless versions of the theory. The problems which appear when calculating the RG improved effective Lagrangian for gauge theories are discussed, taking as example the asymptotically free SU(2) gauge model. 1 E-mail: eli @ ebubecm1.bitnet 2 E-mail: odintsov @ ebubecm1.bitnet