Interacting field theories in Robertson-Walker spacetimes: Analytic approximations (Q1597498)

For a Robertson-Walker universe model, a quantum scalar field is discussed. This scalar field has mass, non-minimal coupling to gravity, and a quartic self-interaction term. For the quantization, the scalar field is decomposed into a classical background field and a quantum field with vanishing mean value. The authors discuss the adiabatic regularization, and analytic approximations to get a renormalized scalar field. As a result, they get an effective energy-momentum tensor. The authors discuss in detail, which parts of the energy-momentum tensors are conserved and which are not.