String-inspired ultraviolet/infrared mixing and preliminary evidence of a violation of the de Broglie relation for nonrelativistic neutrons

TL;DR

This paper explores how noncommutative spacetime models, inspired by string theory and loop quantum gravity, may cause violations of the de Broglie relation, supported by experimental evidence from neutron-based measurements.

Contribution

It introduces a novel hypothesis linking ultraviolet/infrared mixing in quantum spacetime to deviations in the de Broglie relation, supported by experimental data.

Findings

Evidence of non-zero deviation parameter χ from neutron experiments

Proposal of ultraviolet/infrared mixing causing de Broglie relation anomaly

Comparison of fine structure constant measurements supports hypothesis

Abstract

We advocate a novel perspective on the phenomenology of a framework with spacetime noncommutativity which is of established relevance for string theory. Our analysis applies to cases in which the noncommutativity parameters are arranged according to the criteria of "light-like noncommutativity" and ultraviolet supersymmetry is assumed, so that the implications of the characteristic mechanism of ultraviolet/infrared mixing are relatively soft. We also observe that an analogous case of soft ultraviolet-infrared mixing is present in a previously-proposed Loop-quantum-gravity-inspired description of quantum spacetime. And we show that soft ultraviolet-infrared mixing produces an anomaly for the nonrelativistic de Broglie relation $\lambda v = h/m$, with correction term governed by a single (but particle-dependent) parameter $\chi$. We test this hypothesis by comparing a determination of the fine structure constant that relies on the de Broglie relation for nonrelativistic neutrons to other independent determinations of the fine structure constant, and we obtain an estimate of $\chi$ that differs from 0 with four-standard-deviation significance.