Fields on Curved Backgrounds (FoCus)

Principal Investigator: Stefano Ansoldi


  • Early Universe
  • Theory and Phenomenology of Gravity

Abstract: The theory of quantum fields on curved backgrounds is a classic subject in theoretical/mathematical physics that has contributed to the development of fundamental and far reaching ideas, from quantum cosmology to black hole thermodynamics. In this more general framework than standard quantum field theory, we need new conceptual tools, as, often, we cannot consistently use standard techniques and ideas. With this proposal we aim to create a collaborative environment to study in detail open problems in the field, and the related phenomenology, with an interdisciplinary approach.

Status of project and perspectives: The project has developed along the following research lines:

i) One of our research topics has been the study of symmetry breaking and symmetry restoration, in particular, in a preliminary model that has been discussed in the literature with inconsistent interpretation and in connection with the Unruh effect. After clarifying, both, at the technical and conceptual level this model, our future plans are to generalize it to situations, where curvature is present (and of which the already considered case can be interpreted as a local approximation).

ii) Another research topic has been  the study of the robustness of scalar-tensor correlators in the effective theory of inflation: we studied, in particular, two-points and three-point correlation function, in connection with the generation of non-Gaussianities from inflation.

iii) We considered possible generalizations of recently proposed models of traversable wormholes, which consider the propagation of fermions and their Casimir energy in such a non-trivial background. In particular, we analysed extension to non-linear electrodynamics of such models. We plan to extend such models with a more rigorous treatment of the fermions dynamics in axisymmetric spacetimes with a ‘uniform at infinity’ magnetic field.

iv) We explored how to extend black hole thermodynamics in modified theory of gravity. In particular in generalised scalar tensor theories and in theories with preferred frame. In the latter case we have clarified a long standing issue concerning Hawking radiation from universal horizons. We plan to further progress in these fields in the next future.

The first three topics have been investigated, respectively, in the Master thesis of Marco Pasini (in collaboration with dr. Antonino Flachi), the Master thesis of Jacopo Salvalaggio (in collaboration with dr. Giovanni Cabass) and the Master thesis of Alessia Cardinali (in collaboration with dr. Antonio Pittelli). Because of the ongoing pandemic, in the last years most of the interactions have taken place on-line, sometimes using IFPU video conference facilities, other times from home. We plan to increase the direct interaction of participants in the next years, and we will consider the possibility to host a topical workshop on the subject.