The anti-proton charge radius

TL;DR

This paper proposes a new experimental scheme to measure the Lamb shift in anti-hydrogen, aiming to determine the anti-proton charge radius with 10% accuracy, testing CPT symmetry.

Contribution

It introduces a novel method for measuring the anti-proton charge radius using upcoming CERN antiproton facilities and estimates its potential precision.

Findings

Anticipated 100 ppm uncertainty in Lamb shift measurement

First determination of anti-proton charge radius at 10% level

Test of CPT symmetry through anti-hydrogen spectroscopy

Abstract

The upcoming operation of the Extra Low ENergy Antiprotons (ELENA) ring at CERN, the upgrade of the anti-proton decelerator (AD), and the installation in the AD hall of an intense slow positron beam with an expected flux of $10^{8}$ e$^+$/s will open the possibility for new experiments with anti-hydrogen ($\bar{\text{H}}$). Here we propose a scheme to measure the Lamb shift of $\bar{\text{H}}$. For a month of data taking, we anticipate an uncertainty of 100 ppm. This will provide a test of CPT and the first determination of the anti-proton charge radius at the level of 10%.