Towards a holographic description of cosmology: Renormalisation of the energy-momentum tensor of the dual QFT

TL;DR

This paper develops a non-perturbative renormalisation method for the energy-momentum tensor in a holographic cosmology model, enabling predictions of CMB spectra from a dual quantum field theory.

Contribution

It introduces a non-perturbative procedure to renormalise the energy-momentum tensor in a 3D holographic QFT, addressing divergences due to lattice translational invariance loss.

Findings

Renormalisation method removes divergences non-perturbatively.

Enables predictions of CMB power spectra from dual QFT.

Addresses non-perturbative regimes in holographic cosmology.

Abstract

In the holographic approach to cosmology, cosmological observables are described in terms of correlators of a three-dimensional boundary quantum field theory. As a concrete model, we study the 3$d$ massless $SU(N)$ scalar matrix field theory. In this work, we focus on the renormalisation of the energy-momentum tensor 2-point function, which can be related to the CMB power spectra. Here we present a non-perturbative procedure to remove divergences resulting from the loss of translational invariance on the lattice, by imposing Ward identities. This will allow us to make predictions for the CMB power spectra in the regime where the dual QFT is non-perturbative.