Naturalness in emergent spacetime

TL;DR

This paper explores an emergent spacetime model using two-component BECs to simulate Lorentz violations, addressing the naturalness problem and offering insights for quantum gravity phenomenology.

Contribution

It introduces a condensed-matter analogue model that demonstrates how to avoid the naturalness problem in Lorentz violation scenarios.

Findings

Model simulates Lorentz violations due to ultraviolet physics.

Explicitly avoids the naturalness problem.

Provides suggestions for quantum gravity phenomenology.

Abstract

Effective field theories (EFTs) have been widely used as a framework in order to place constraints on the Planck suppressed Lorentz violations predicted by various models of quantum gravity. There are however technical problems in the EFT framework when it comes to ensuring that small Lorentz violations remain small -- this is the essence of the "naturalness" problem. Herein we present an "emergent" space-time model, based on the "analogue gravity'' programme, by investigating a specific condensed-matter system that is in principle capable of simulating the salient features of an EFT framework with Lorentz violations. Specifically, we consider the class of two-component BECs subject to laser-induced transitions between the components, and we show that this model is an example for Lorentz invariance violation due to ultraviolet physics. Furthermore our model explicitly avoids the "naturalness problem", and makes specific suggestions regarding how to construct a physically reasonable quantum gravity phenomenology.