We use different methods to calculate the imaginary part of the gravitational effective action
due to a massless scalar field, with a view on perturbative vs nonpertubative and the results …

We consider a massive scalar field theory on static four-dimensional space–times with
horizons. We study the near horizon behavior of the quantum expectation values of the …

We discuss two distinct operator-theoretic settings useful for describing (or defining)
propagators associated with a scalar Klein-Gordon field on a Lorentzian manifold $ M …

We construct explicit mode expansions of various tree-level propagators in the Rindler–de
Sitter universe, also known as the static (or compact) patch of the de Sitter spacetime. We …

We consider two approaches to calculate imaginary parts of effective actions in expanding
space-times. While the first approach uses Bogolyubov coefficients, the second one uses the …

We consider interacting massive scalar quantum field theory in the future Rindler wedge.
This is a model example of quantum field theory in curved space-time. Using this simple …

A bstract The Euclidean path integral is compared to the thermal (canonical) partition
function in curved static space-times. It is shown that if spatial sections are non-compact and …

We study quantum fields on spacetimes having a bifurcate Killing horizon by allowing the
possibility that left and right (ingoing and outgoing) modes have different temperatures. An …

We investigate the free energy and entropy of the Gaussian massive scalar field theory in
the static de Sitter space-time for arbitrary temperature. For the inverse temperatures of the …

A bstract An integral representation of the 1-loop partition function for charged scalars and
spinors, minimally coupled to a uniform U (1) field on S 2, is given in terms of SO (1, 2) …