On the sensitivity of nuclear clocks to new physics

TL;DR

This paper explores how nuclear clocks based on Thorium-229's isomeric state can be highly sensitive to new physics, with potential sensitivity enhancements of around 10,000 times, using novel nuclear models.

Contribution

It introduces a geometric and a $d$-wave halo nuclear model to quantify the sensitivity of nuclear clocks to new physics, highlighting potential large enhancements.

Findings

Potential sensitivity enhancement of about 10^4 times.

A worst-case scenario with negligible enhancement is unlikely.

The models reproduce measured differences between Thorium-229 states.

Abstract

The recent demonstration of laser excitation of the $\approx 8$ eV isomeric state of Thorium-229 is a significant step towards a nuclear clock. The low excitation energy likely results from a cancellation between electromagnetic and strong contributions, which new physics can disrupt. In this Letter, we quantify the enhancement of a nuclear clock's sensitivity to new physics using a geometric model and a novel $d$-wave halo model of the nucleus that reproduces measured differences between Thorium-229 states. We find likely enhancements of order $10^4$ while a worst case scenario with enhancement $\ll 1$ is unlikely.