New physics in \epsilon' from chromomagnetic contributions and limits on Left-Right symmetry

TL;DR

This paper investigates how chromomagnetic contributions from new physics can significantly affect CP violation in kaon decays, providing bounds on Left-Right symmetry models and their parameters.

Contribution

It introduces a numeric formula for epsilon' in terms of short-distance coefficients applicable to various new physics models, highlighting constraints on Left-Right symmetry.

Findings

Chromomagnetic contributions can enhance epsilon' significantly.

Bounds on right-handed quark mixing phases are derived.

Constraints on Left-Right symmetry scale are established.

Abstract

New physics in the chromomagnetic flavor changing transition s->dg* can avoid the strong GIM suppression of the Standard Model and lead to large contributions to CP-violating observables, in particular to the epsilon' parameter, that we address here. We discuss the case of the Left-Right symmetric models, where this contribution implies bounds on the phases of the right-handed quark mixing matrix, or in generic models with large phases a strong bound on the Left-Right symmetry scale. To the leading order, a numeric formula for epsilon' as a function of the short-distance coefficients for a wide class of models of new physics is given.