Probing new hadronic forces with heavy exotic atoms

TL;DR

This paper proposes using precision spectroscopy of heavy exotic atoms with hadronic substitutions to detect new force carriers, providing a novel method to set bounds on mediator masses and improve sensitivity to new physics.

Contribution

It introduces a new approach using exotic atom spectroscopy to probe hadronic forces and demonstrates how existing data can set competitive bounds on mediator particles.

Findings

Existing data yields leading bounds on mediator masses from 0.1 to 10 MeV.

Forthcoming experiments could improve sensitivity by two orders of magnitude.

Selected transitions are unaffected by nuclear contact terms, enabling precise calculations.

Abstract

We explore the potential of precision spectroscopy of heavy exotic atoms where electrons are substituted by negative hadrons to detect new force carriers with hadronic couplings. The selected transitions are unaffected by nuclear contact terms, thus enabling highly accurate calculations using bound-state QED, provided that the nuclear polarization is under control. Alternatively, we demonstrate that the dipole polarizability, a fundamental property of nuclei, can be extracted from the spectroscopy of exotic atoms in a novel way by combining two transitions while maintaining high sensitivity to new physics. Based on existing data, we extracted world-leading bounds on mediator masses ranging from $0.1\,$MeV to $10\,$MeV for two benchmark models and show that forthcoming experiments could enhance the sensitivity to new physics by two orders of magnitude.