arXiv subjects

Michael S. Ruf

Publications and source records attributed to Michael S. Ruf.

21 records · Page 2Linked to original sources

arXiv2018

Renormalization of generalized vector field models in curved spacetime

We calculate the one-loop divergences for different vector field models in curved spacetime. We introduce a classification scheme based on their degeneracy structure, which encompasses the well-known models of the non-degenerate vector field, the Abelian gauge field and the Proca field. The renormalization of the generalized Proca model, which has important applications in cosmology, is more complicated. By extending standard heat-kernel techniques, we derive a closed form expression for the one-loop divergences of the generalized Proca model.

hep-th↗

arXiv2018

One-loop divergences for $f(R)$ gravity

We calculate the divergent part of the one-loop effective action for $f(R)$ gravity on an arbitrary background manifold. Our result generalizes previous results for quantum corrections in $f(R)$ gravity, which have been limited to spaces of constant curvature. We discuss a new technical aspect connected to operators with degenerate principal symbol. Our result has important applications in cosmology and allows to study the quantum equivalence between $f(R)$ theories and scalar-tensor theories.

gr-qc↗

arXiv2018

Quantum equivalence of $f(R)$ gravity and scalar-tensor theories

We investigate whether the classical equivalence of $f(R)$ gravity and its formulation as scalar-tensor theory still holds at the quantum level. We explicitly compare the corresponding one-loop divergences and find that the equivalence is broken by off-shell quantum corrections, but recovered on-shell.

gr-qc↗