# Development of a cold atomic muonium beam for next generation atomic physics and gravity experiments

### Submission summary

 As Contributors: Anna Soter Preprint link: scipost_202106_00044v2 Date accepted: 2021-08-12 Date submitted: 2021-08-01 13:06 Submitted by: Soter, Anna Submitted to: SciPost Physics Proceedings Proceedings issue: Review of Particle Physics at PSI Academic field: Physics Specialties: Atomic, Molecular and Optical Physics - Experiment Approach: Experimental

### Abstract

A high-intensity, low-emittance atomic muonium (M) beam is being developed, which would enable improving the precision of M spectroscopy measurements, and may allow a direct observation of the M gravitational interaction. Measuring the free fall of M atoms would be the first test of the weak equivalence principle using elementary antimatter ($\mu^+$) and a purely leptonic system. Such an experiment relies on the high intensity, continuous muon beams available at the Paul Scherrer Institute (PSI, Switzerland), and a proposed novel M source. In this paper, the theoretical motivation and principles of this experiment are described.

Published as SciPost Phys. Proc. 5, 031 (2021)

Minor revisions requested by Referee 2 were addressed.

### List of changes

Minor revisions requested by Referee 2 were addressed, see details and list of changes in Reply to Referee.