Signature of new physics in B -> phi pi decay

TL;DR

This paper explores how new physics, such as a fourth quark generation and FCNC mediated Z and Z' bosons, could significantly enhance the rare B- to phi pi- decay rate and CP violation, making it a sensitive probe for physics beyond the Standard Model.

Contribution

It demonstrates that new physics contributions can greatly increase the branching ratio and CP violation in B- to phi pi- decay, which are negligible in the Standard Model.

Findings

Significant enhancement of the decay's branching ratio due to new physics.

Non-zero direct CP violation parameter in the presence of new physics.

Potential to constrain new physics parameters through upcoming experiments.

Abstract

We investigate the effect of an extra fourth quark generation and FCNC mediated $Z$ and $Z'$ bosons on the rare decay mode $B^- \to \phi \pi^-$. In the standard model, this mode receives only $b \to d$ penguin contributions and therefore, highly suppressed with branching ratio $\sim 5 \times 10^{-9}$. This in turn makes this mode a very sensitive probe for new physics. We find that due to the above mentioned new physics contributions there is a significant enhancement in its branching ratio. Furthermore, the direct CP violation parameter which is identically zero in the SM is found to be quite significant. If this mode will be observed in the upcoming LHCb experiment, it will not only provide a clear signal of new physics but also can be used to constrain the new physics parameter space.