Constraining CP violation in neutral meson mixing with theory input

TL;DR

This paper develops a new theoretical relation for neutral meson mixing parameters, enhancing the interpretation of CP violation data and revealing stronger tensions with the Standard Model, especially in semileptonic CP asymmetry measurements.

Contribution

It introduces a novel relation for mixing parameters that clarifies data interpretation in models with new physics contributions to M_12 and/or Γ_12.

Findings

The DØ measurement of semileptonic CP asymmetry conflicts with the Standard Model.

The tension with ΔΓ_s data is stronger than previously thought.

The new relation can tighten constraints on ΔΓ or A_SL measurements.

Abstract

There has been a lot of recent interest in the experimental hints of CP violation in B_{d,s}^0 mixing, which would be a clear signal of beyond the standard model physics (with higher significance). We derive a new relation for the mixing parameters, which allows clearer interpretation of the data in models in which new physics enters in M_12 and/or \Gamma_12. Our results imply that the central value of the D\O\ measurement of the semileptonic CP asymmetry in B_{d,s}^0 decay is not only in conflict with the standard model, but in a stronger tension with data on \Delta\Gamma_s than previously appreciated. This result can be used to improve the constraint on \Delta\Gamma or A_SL, whichever is less precisely measured.