Precise measurement of Hyper Fine Structure of positronium using sub-THz light

TL;DR

This paper proposes a new method using a gyrotron and high-finesse cavity to precisely measure the hyperfine splitting of positronium at 203 GHz, aiming to resolve discrepancies with QED predictions.

Contribution

It introduces a novel experimental setup employing sub-THz light and a gyrotron for direct, high-precision HFS measurement of positronium, addressing systematic issues in previous experiments.

Findings

Design of a high-power 203 GHz radiation source

Optimization of the experimental setup for precise measurement

Current progress in experimental implementation

Abstract

Positronium is an ideal system for the research of the QED, especially for the QED in bound state. The discrepancy of 3.9\sigma is found recently between the measured HFS values and the QED prediction ($O(\alpha^3)$). It might be due to the contribution of the unknown new physics or the systematic problems in the previous all measurements. We propose new method to measure HFS precisely and directly. A gyrotron, a novel sub-THz light source is used with a high-finesse Fabry-P\'erot cavity to obtain enough radiation power at 203 GHz. The present status of the optimization studies and current design of the experiment are described.