$\epsilon'$ from right-handed currents

TL;DR

This paper explores whether right-handed charged currents can explain the discrepancy in direct CP violation measurements in kaon decays, linking theoretical calculations with experimental constraints from electric dipole moments.

Contribution

It introduces a method combining chiral perturbation theory and lattice QCD to assess right-handed currents' impact on psilon' and connects this to electric dipole moment constraints.

Findings

Right-handed currents can potentially resolve the psilon' discrepancy.

Next-generation electric dipole moment experiments can test this scenario.

The approach provides a direct link between CP violation and hadronic electric dipole moments.

Abstract

Recent lattice determinations of direct CP violation in kaon decays, parametrized by $\epsilon'$, suggest a discrepancy of several sigma between experiment and the standard model. Assuming that this situation is due to new physics, we investigate a solution in terms of right-handed charged currents. Chiral perturbation theory, in combination with lattice QCD results, allows one to accurately determine the effect of right-handed interactions on $\epsilon'$. In addition, similar techniques provide a direct link between the right-handed contributions to $\epsilon'$ and hadronic electric dipole moments. We demonstrate that the $\epsilon'$ discrepancy can be resolved with right-handed charged currents, and that this scenario can be falsified by next-generation hadronic electric dipole moment experiments.