itle: Anomaly-induced vacuum effective action with torsion: covariant solution and ambiguities


Speaker: Ilya L. Shapiro (Universidade Federal de Juiz de Fora, MG, Brazil)


Abstract: Torsion gravity, or Einstein-Cartan theory, is the simplest way to go beyond the framework of general relativity. The main advantage of torsion is the possibility of linking the spin of fermionic matter to spacetime geometry. Semiclassical gravity with torsion has been consistently formulated in 80-is, including the renormalizable theory and derivation of conformal anomaly. After a brief review of the subject, I will report on the new results concerning the covariant nonlocal form of the anomaly-induced effective action. This action manifests a qualitatively new kind of ambiguity coming from the multiplicative anomaly in the fermionic contribution. This ambiguity concerns total derivative terms in the anomaly or, equivalently, the local nonconformal terms in the effective action. On the other hand, the nonlocal part of anomaly-induced effective action is free of ambiguity and admits a low-energy limit in a form similar to the effective potential in the scalar theory.