Small Lorentz violations in quantum gravity: do they lead to unacceptably large effects?

TL;DR

This paper examines whether small Lorentz violations predicted by loop quantum gravity could lead to observable effects at low energies, challenging previous perturbative arguments.

Contribution

It analyzes non-perturbative effects in loop quantum gravity and their potential to avoid large low-energy Lorentz violations.

Findings

Non-perturbative effects may suppress low-energy Lorentz violations.

Perturbative arguments may not fully apply to loop quantum gravity.

Potential for small Lorentz violations without observable consequences.

Abstract

We discuss the applicability of the argument of Collins, P\'erez, Sudarsky, Urrutia and Vucetich to loop quantum gravity. This argument suggests that Lorentz violations, even ones that only manifest themselves at energies close to the Planck scale, have significant observational consequences at low energies when one considers perturbative quantum field theory and renormalization. We show that non-perturbative treatments like those of loop quantum gravity may generate deviations of Lorentz invariance of a different type than those considered by Collins et al. that do not necessarily imply observational consequences at low energy.