Related papers: Resumming Fermion Loops for Inflationary Gravity
A Lagrange multiplier field can be used to restrict radiative corrections to the Einstein-Hilbert action to one-loop order. This result is employed to show that it is possible to couple a scalar field to the metric (graviton) field in such…
In this paper we study the cosmological constant emerging from the Wheeler-DeWitt equation as an eigenvalue of the related Sturm-Liouville problem. We employ Gaussian trial functionals and we perform a mode decomposition to extract the…
I report on work done with Tomislav Prokopec (Heidelberg, CERN). We computed the one loop self-energy of a massless fermion during inflation. When the fermion is free it experiences only a small amount of inflationary particle production…
It is widely believed that the leading secular loop corrections from quantum gravity can be subsumed into a coordinate redefinition. Hence the apparent infrared logarithm corrections to any quantity would be just the result of taking the…
We compute the leading-order back-reaction to dilaton-driven inflation, due to graviton, dilaton and gauge-boson production. The one-loop effect turns out to be non-vanishing (unlike the case for pure de-Sitter and for power-law inflation),…
The availability of scaling solutions in renormalisation group improved versions of cosmology are investigated in the high-energy limit. We adopt $f(R)$-type models of quantum gravity which display an interacting ultraviolet fixed point at…
Recently in the framework of a two-loop order calculation for an effective field theory of scalar and vector fields interacting with the metric field we have shown that for the cosmological constant term which is fixed by the condition of…
I present the two-loop self-energy functions and pole masses for fermions in an arbitrary renormalizable field theory, in the approximation that vector bosons are treated as massless. The calculations are done simultaneously in the…
We compute the one-loop quantum corrections to the potential of ghost-free massive gravity. We show how the mass of external matter fields contribute to the running of the cosmological constant, but do not change the ghost-free structure of…
The two-point function for tensor metric perturbations around de Sitter spacetime including one-loop corrections from massless conformally coupled scalar fields is calculated exactly. We work in the Poincar\'e patch (with spatially flat…
We compute the Zero Point Energy in a spherically symmetric background combining the high energy distortion of Gravity's Rainbow with the modification induced by a f(R) theory. Here f(R) is a generic analytic function of the Ricci curvature…
We study a system of self-gravitating massive fermions in the framework of the general-relativistic Thomas-Fermi model. We postulate the free energy functional and show that its extremization is equivalent to solving the Einstein's field…
We consider a massless and minimally coupled self interacting quantum scalar field in the inflationary de Sitter spacetime. The scalar potential is taken to be a hybrid, $V(\phi)= \lambda \phi^4/4!+\beta \phi^3/3!$ ($\lambda >0$). Compared…
The quantum gravitational back-reaction on inflation is based on the self-gravitation of infrared gravitons which are ripped out of the vacuum during inflation. The only quantum part of this process is the creation of gravitons; after they…
This paper investigates the coupling of massive fermions to gravity within the context of a non-Abelian gauge theory, utilizing the effective field theory framework for quantum gravity. Specifically, we calculate the two-loop beta function…
We treat a model in which tensor perturbations of de~Sitter spacetime, represented as a spatially flat model, are modified by the effects of the vacuum fluctuations of a massless conformally invariant field, such as the electromagnetic…
This paper focuses on the search for a coherent and consistent formulation to describe quantum gravity corrections to Quantum Field Theory. We implement two fundamental ingredients discussed in previous analyses: on one hand, the…
We investigate the one-loop quantum correction to the power spectrum of primordial curvature perturbations in the ultra-slow-roll (USR) inflationary scenario, incorporating the backreaction effect from curvature perturbations. In the…
Perturbative quantum field theory (QFT) calculations in de Sitter space are riddled with contributions that diverge over time. These contributions often arise from loop integrals, which are notoriously hard to compute in de Sitter. We…
The empty space (with no matter fields) is not really empty because of natural metric fluctuations, quantum and classical. We show that gravitons as well as classical gravitational waves of super-horizon wavelengths are able to form the de…