Correlations among new CP violating effects in Delta F = 2 observables

TL;DR

The paper investigates potential new sources of CP violation in meson mixing observables, suggesting that current measurements may hint at physics beyond the Standard Model and highlighting the importance of precise parameter determinations.

Contribution

It identifies correlations among CP violating effects in Delta F=2 processes and explores how new physics could resolve existing tensions in measurements.

Findings

Standard Model may be insufficient to explain epsilon_K with current data.

A common new CP phase could reconcile epsilon_K and S_{psi Ks} measurements.

Precise measurements of Vcb, BK, FK, and xi_s are crucial for understanding CP violation correlations.

Abstract

We point out that the observed CP violation in Bd - bar{Bd} mixing, taking into account the measured ratio Delta Md / Delta Ms, the recently improved lattice value of the non-perturbative parameter BK and an additional effective suppression factor kappa_epsilon ~= 0.92 in epsilon_K neglected sofar in most analyses, may be insufficient to describe the measured value of epsilon_K within the Standard Model (SM), thus hinting at new CP violating contributions to the K - bar{K} and/or Bd - bar{Bd} systems. Furthermore, assuming that Delta Md / Delta Ms is SM-like, the signs and the magnitudes of new physics effects in epsilon_K and in the CP asymmetries S_{psi Ks} and S_{psi phi} may turn out to be correlated. For example, in a scenario with new CP-phases in Bd and Bs mixings being approximately equal and negative, a common new phase ~= - 5 degrees could remove the tension between epsilon_K and S_{psi Ks} present in the SM and simultaneously accommodate, at least partly, the recent claim of S_{psi phi} being much larger than the SM expectation. We emphasize the importance of precise determinations of Vcb, BK, FK and xi_s, to which the parameter epsilon_K and its correlation with the CP violation in the Bd - bar{Bd} system are very sensitive.