Limiting Lorentz Violation from Neutron--Antineutron Oscillation

TL;DR

Observation of neutron-antineutron oscillation in free neutron experiments can set the most stringent limits on Lorentz invariance violation for neutrons, constraining LIV operators to extremely small levels and clarifying their detectability in different experimental setups.

Contribution

The paper demonstrates that free neutron oscillation experiments can impose tight bounds on LIV operators and analyzes the effects of nuclear environments on LIV detection.

Findings

Free neutron oscillation experiments constrain LIV operators to ~10^{-23} GeV.

Nuclear decay experiments do not provide limits on LIV due to nuclear potential masking.

Certain LIV operators can produce observable signals without degaussing.

Abstract

We point out that if neutron--antineutron oscillation is observed in a free neutron oscillation experiment, it will put an upper limit on the strengths of Lorentz invariance violating (LIV) mass operators for neutrons at the level of $10^{-23}$ GeV or so, which would be the most stringent LIV limit for neutrons. We also study constraints on $\Delta B=2$ LIV operators and find that for one particular operator degaussing is not necessary to obtain a visible signal. We also note that observation of $n-\bar{n}$ oscillation signal in the nucleon decay search experiment involving nuclei does not lead to any limit on LIV operators since the nuclear potential difference between neutron and antineutrons will mask any Lorentz violating effect.