Measuring gravitational effects on antimatter in space

TL;DR

This paper proposes an experiment in space to test how gravity affects antimatter by observing CP violation in kaon decays, potentially revealing new gravitational interactions with antimatter.

Contribution

It introduces a novel space-based experimental approach to measure gravitational effects on antimatter through CP violation in kaon decays, which has not been previously explored.

Findings

Gravitational effects could alter CP violation levels at ISS altitude.

A 5-sigma discrimination is achievable within a few years of data collection.

Space-based measurements can provide new insights into antimatter gravity interactions.

Abstract

We propose an experimental test of the gravitational interaction with antimatter by measuring the branching fraction of the CP~violating decay $K_\mathrm{L} \to \pi^{+} \pi^{-}$ in space. We show that at the altitude of the International Space Station, gravitational effects may change the level of CP~violation such that a 5$\sigma$ discrimination may be obtained by collecting the $K_\mathrm{L}$ produced by the cosmic proton flux within a few years.