On the Universality of CP Violation in Delta F = 1 Processes

TL;DR

This paper demonstrates that certain new physics breaking flavor symmetry induces universal CP violation effects in Delta F = 1 processes, constraining models and explaining recent experimental results.

Contribution

It proves the universality of CP violation contributions from SU(3)_Q breaking new physics and explores implications for supersymmetric models and experimental bounds.

Findings

Universal CP violation contributions are constrained by existing bounds.

SU(3)_Q breaking cannot explain recent LHCb CP violation in D decays.

Future measurements will test supersymmetric alignment models.

Abstract

We show that new physics which breaks the left-handed SU(3)_Q quark flavor symmetry induces contributions to CP violation in Delta F = 1 couplings which are approximately universal, in that they are not affected by flavor rotations between the up and the down mass bases. (Only the short distance contributions are universal, while observables are also affected by hadronic matrix elements.) Therefore, such flavor violation cannot be aligned, and is constrained by the strongest bound from either the up or the down sectors. We use this result to show that the bound from eps'/eps prohibits an SU(3)_Q breaking explanation of the recent LHCb evidence for CP violation in D meson decays. Another consequence of this universality is that supersymmetric alignment models with a moderate mediation scale are consistent with the data, and are harder to probe via CP violating observables. With current constraints, therefore, squarks need not be degenerate. However, future improvements in the measurement of CP violation in D-Dbar mixing will start to probe alignment models.