Towards Precision Spectroscopy of Antiprotonic Atoms for Probing Strong-field QED

TL;DR

The PAX experiment aims to perform high-precision x-ray spectroscopy of antiprotonic atoms to test strong-field QED effects, utilizing advanced detection and low-energy antiproton beams to achieve unprecedented accuracy.

Contribution

It introduces a novel experimental approach combining microcalorimeter detection and low-energy antiprotons to directly measure strong-field QED effects without nuclear uncertainties.

Findings

Enhanced measurement accuracy over previous studies.

Ability to probe electric fields above the Schwinger limit.

Potential to test vacuum polarization and second-order QED corrections.

Abstract

PAX (antiProtonic Atom X-ray spectroscopy) is a new experiment with the aim to test strong-field quantum electrodynamics (QED) effects by performing high-precision x-ray spectroscopy of antiprotonic atoms. By utilizing advanced microcalorimeter detection techniques and a low-energy antiproton beam provided by the ELENA ring at CERN, gaseous targets will be used for the creation of antiprotonic atoms, and the measurement of transitions between circular Rydberg states will be conducted with up to two orders of magnitude improved accuracy over previous studies using high-purity germanium detectors. Our approach eliminates the longstanding issue of nuclear uncertainties that have hindered prior studies using highly charged ions, thus enabling direct and purely QED-focused measurements. By precisely probing atomic systems with electric fields up to two orders of magnitude above the Schwinger limit, PAX will test vacuum polarization and second-order QED corrections, opening new frontiers in fundamental physics and uncovering potential pathways to physics beyond the Standard Model.