Search for Pauli Exclusion Principle Violations with Gator at LNGS

TL;DR

This study used a high-purity germanium detector at LNGS to perform a sensitive search for violations of the Pauli Exclusion Principle in lead atoms, setting a new upper limit that surpasses previous constraints by over ten times.

Contribution

It presents the first dedicated experimental test of PEP violations using the Gator detector, achieving significantly improved upper limits on violation probability.

Findings

No PEP violations observed within experimental sensitivity.

Set an upper limit on PEP violation probability of < 4.8 x 10^{-29}.

Improved previous constraints by more than an order of magnitude.

Abstract

The Pauli Exclusion Principle (PEP) appears from fundamental symmetries in quantum field theories, but its physical origin is still to be understood. High-precision experimental searches for small PEP violations permit testing key assumptions of the Standard Model with high sensitivity. We report on a dedicated measurement with Gator, a low-background, high-purity germanium detector operated at the Laboratori Nazionali del Gran Sasso, aimed at testing PEP-violating atomic transitions in lead. The experimental technique, relying on forming a new symmetry state by introducing electrons into the pre-existing electron system through a direct current, satisfies the conditions of the Messiah-Greenberg superselection rule. No PEP violation has been observed, and an upper limit on the PEP violation probability of $\beta^2/2 < 4.8 \cdot 10^{-29}$ (90% CL) is set. This improves the previous constraint from a comparable measurement by more than one order of magnitude.