Prospects of In-Flight Hyperfine Spectroscopy of (Anti)Hydrogen for Tests of CPT Symmetry

TL;DR

This paper discusses the potential of in-flight hyperfine spectroscopy of (anti)hydrogen to test CPT symmetry, highlighting recent measurements and future prospects for probing fundamental physics.

Contribution

It presents the development of a polarized hydrogen source and initial hyperfine transition measurements, enabling new tests of CPT symmetry and Standard-Model Extension coefficients.

Findings

Hydrogen $ extsigma_1$ transition measured to a few ppb precision.

A polarized cold hydrogen source was successfully built.

Preparation for $ extpi_1$ transition measurement is underway.

Abstract

The ground-state hyperfine splitting of antihydrogen promises one of the most sensitive tests of CPT symmetry. The ASACUSA collaboration is pursuing a measurement of this splitting in a Rabi-type experiment using a polarized beam from a CUSP magnet at the Antiproton Decelerator of CERN. With the initial intention of characterizing the Rabi apparatus, a polarized source of cold hydrogen was built and the $\sigma_1$ transition of hydrogen was measured to a few ppb precision. A measurement of the $\pi_1$ transition is being prepared. The availability of this beam opens the possibility to perform first measurements of some coefficients within the nonminimal Standard-Model Extension.