# Quantum corrections for spinning particles in de Sitter

## TL;DR

This paper calculates one-loop quantum corrections to the gravitational field of a spinning particle in de Sitter space, revealing a large-distance enhancement of gravity due to quantum effects.

## Contribution

It provides a gauge-invariant computation of quantum corrections for spinning particles in de Sitter, including a novel logarithmic term affecting large-distance gravity.

## Key findings

- Quantum corrections include a flat-space-like term, a constant, and a logarithmic growth with distance.
- The logarithmic correction leads to a modified power law, strengthening gravity at large scales.
- Results recover classical Kerr-de Sitter and flat-space quantum corrections in appropriate limits.

## Abstract

We compute the one-loop quantum corrections to the gravitational potentials of a spinning point particle in a de Sitter background, due to the vacuum polarisation induced by conformal fields in an effective field theory approach. We consider arbitrary conformal field theories, assuming only that the theory contains a large number $N$ of fields in order to separate their contribution from the one induced by virtual gravitons. The corrections are described in a gauge-invariant way, classifying the induced metric perturbations around the de Sitter background according to their behaviour under transformations on equal-time hypersurfaces. There are six gauge-invariant modes: two scalar Bardeen potentials, one transverse vector and one transverse traceless tensor, of which one scalar and the vector couple to the spinning particle. The quantum corrections consist of three different parts: a generalisation of the flat-space correction, which is only significant at distances of the order of the Planck length; a constant correction depending on the undetermined parameters of the renormalised effective action; and a term which grows logarithmically with the distance from the particle. This last term is the most interesting, and when resummed gives a modified power law, enhancing the gravitational force at large distances. As a check on the accuracy of our calculation, we recover the linearised Kerr-de Sitter metric in the classical limit and the flat-space quantum correction in the limit of vanishing Hubble constant.