Causal sets and conservation laws in tests of Lorentz symmetry

TL;DR

This paper examines how violations of energy-momentum conservation in causal set quantum gravity could falsely suggest Lorentz symmetry violations in astrophysical tests, but finds such effects are currently undetectable.

Contribution

It demonstrates that energy-momentum non-conservation in causal sets can produce false signals of Lorentz violation, clarifying the robustness of current astrophysical tests.

Findings

Spurious Lorentz violation signals are smaller than current detection thresholds.

Astrophysical tests remain valid despite potential causal set violations.

Energy-momentum conservation assumptions are safe for current experiments.

Abstract

Many of the most important astrophysical tests of Lorentz symmetry also assume that energy-momentum of the observed particles is exactly conserved. In the causal set approach to quantum gravity a particular kind of Lorentz symmetry holds but energy-momentum conservation may be violated. We show that incorrectly assuming exact conservation can give rise to a spurious signal of Lorentz symmetry violation for a causal set. However, the size of this spurious signal is much smaller than can be currently detected and hence astrophysical Lorentz symmetry tests as currently performed are safe from causal set induced violations of energy-momentum conservation.