arXiv subjects

A. J. Foraci

Publications and source records attributed to A. J. Foraci.

3 recordsLinked to original sources

arXiv2026

Sensing the Inflationary Production of Scalars

We review the mechanism by which loops of matter fields contribute to the graviton self-energy during de Sitter inflation. The self-energy is used to quantum-correct the linearized Einstein equations. A Green's function method is employed to obtain exact 1-loop corrections to the plane wave mode functions of gravitational radiation, subject to the usual ambiguity in the initial state. Conformally coupled matter, which does not experience inflationary particle production, makes only a logarithmic enhancement of the rate at which the imaginary part of the mode function goes to zero after horizon crossing. These corrections can be understood, and even summed up, using a variant of the renormalization group. However, massless, minimally coupled scalars, which experience massive inflationary particle production, induce a much stronger enhancement of the rate at which the real part of the mode function approaches a constant. One interpretation of this effect is as a shift of the inflationary Hubble parameter.

gr-qc↗

arXiv2024

Resumming Fermion Loops for Inflationary Gravity

We compute the 1-loop contribution to the graviton self-energy from a loop of massless fermions on a general cosmological background. The result is used to quantum-correct the linearized Einstein equation on de Sitter background and work out 1-loop corrections to gravitational radiation and to the response to a point mass. The renormalization group is employed to sum these to all orders for as long as the de Sitter phase persists.

gr-qc↗

arXiv2024

Resumming Photon Loops for Inflationary Gravity

A previous calculation of the 1-loop photon contribution to the graviton self-energy on de Sitter background is considered. We first show that there is no local obstacle to conservation, unlike the contribution from a loop of massless, minimally coupled scalars. This is correlated to the absence of an Eddington ($R^2$) counterterm and to the vanishing of the stress tensor when the photon in integrated out in the presence of a constant graviton field. We also show that there is a secularly growing 1-loop contribution to the electric components of the Weyl tensor for plane wave gravitons. Its coefficient agrees with that of the secular 1-loop correction to the Newtonian potential, and both can be resummed using a variant of the renormalization group.

gr-qc↗