Hints for a Low Bs --> mu+ mu- Rate and the Fourth Generation

TL;DR

This paper discusses the implications of recent LHC data on the Bs --> mu+ mu- decay rate, suggesting a potential suppression that could indicate the presence of a fourth generation of quarks, with specific bounds on their mixing parameters.

Contribution

It provides a theoretical analysis linking potential suppression in Bs --> mu+ mu- decay to constraints on fourth generation quark mixing, based on recent experimental data.

Findings

No deviation from SM in CP violation and asymmetry measurements.

Sensitivity reached for Bs --> mu+ mu- rate, hinting at possible suppression.

Suppression would imply a lower bound on |V_{t's}^*V_{t'b}|.

Abstract

With full 2011 LHC data analyzed, there is no indication for deviation from Standard Model (SM) in CP violating phase for Bs --> J/psi phi, nor in the forward-backward asymmetry for B0 --> K*0 mu+ mu-. SM sensitivity, however, has been reached for Bs --> mu+ mu- rate, and there may be some hint for a suppression. We illustrate that, if a suppressed B(Bs --> mu+ mu-) bears out with 2012 data, it would imply a lower bound on the fourth generation quark mixing product |V_{t's}^*V_{t'b}|.