Bounds on new physics from B_s mixing

TL;DR

This paper reviews constraints on B_s-B_s-bar mixing, introduces a new calculation of the decay matrix element Gamma_{12}^s, and finds a 2-sigma deviation in the mixing phase from the Standard Model using Tevatron data.

Contribution

It provides a novel calculation of Gamma_{12}^s and applies it to experimental data to analyze deviations from the Standard Model in B_s mixing.

Findings

Delta Gamma_s^SM = 0.088 +/- 0.017 ps^(-1)

Deviation of the mixing phase phi_s by 2 standard deviations from SM

Current data do not determine the sign of Delta Gamma_s

Abstract

I summarize the observables constraining the B_s-B_s-bar mixing complex and present a new calculation of the element Gamma_{12}^s of the decay matrix. Gamma_{12}^s enters the prediction of the width difference Delta Gamma_s, for which we obtain Delta Gamma_s^SM = 0.088 +/- 0.017 ps^(-1), if no new physics enters B_s-B_s-bar mixing. Applying our formulae to Tevatron data we find a deviation of the B_s-B_s-bar mixing phase phi_s from its Standard Model value by 2 standard deviations. I stress that present data do not give any information on the sign of Delta Gamma_s.