Experimental hint for gravitational CP violation

TL;DR

This paper proposes a novel high-energy Compton scattering method to test gravitational interactions of charged particles, providing evidence against antimatter anti-gravity and suggesting possible gravitational CP violation at GeV energies.

Contribution

It introduces a new experimental approach using high-energy Compton scattering to investigate gravitational effects on accelerated charged particles, revealing potential gravitational CP violation.

Findings

HERA data rules out antimatter anti-gravity at near 100% confidence.

Evidence suggests gravitational CP violation around 13 GeV energies.

Indications of stronger gravitational coupling to left helicity electrons.

Abstract

An equality of particle and antiparticle gravitational interactions holds in general relativity and is supported by indirect observations. Gravity dependence on rotation or spin direction is experimentally constrained for non-relativistic matter. Here a method based on high energy Compton scattering is developed to measure the gravitational interaction of accelerated charged particles. Within that formalism the Compton spectra measured at HERA rule out the speculated anti-gravity possibility for antimatter at a confidence level close to 100%. The same data, however, imply a gravitational CP violation around 13 GeV energies, by a maximal amount of 9 +/- 2 ppt for the charge and 13 +/- 3 ppt for the space parity. The detected asymmetry hints for a stronger gravitational coupling to left helicity electrons relative to right helicity positrons.