Probing new physics in electroweak penguins through B_d and B_s decays

TL;DR

This paper explores how new physics could enhance electroweak penguin effects in B meson decays, proposing specific decay modes as sensitive probes for future experiments like LHCb and B factories.

Contribution

It identifies ar{B}_s -> phi rho^0 and ar{B}_s -> phi pi^0 decays as promising channels to detect new physics effects in electroweak penguins, expanding the search beyond traditional modes.

Findings

Electroweak penguin amplitudes can be significantly enhanced by new physics.

Branching ratios of specific B_s decays could increase by about an order of magnitude.

These decay modes are promising targets for upcoming experimental investigations.

Abstract

An enhanced electroweak penguin amplitude due to the presence of unknown new physics can explain the discrepancies found between theory and experiment in the B -> pi K decays, in particular in A_CP(B^- -> pi^0 K^-) - A_CP(\bar{B}^0 -> pi^+ K^-), but the current precision of the theoretical and experimental results does not allow to draw a firm conclusion. We argue that the \bar{B}_s -> phi rho^0 and \bar{B}_s -> phi pi^0 decays offer an additional tool to investigate this possibility. These purely isospin-violating decays are dominated by electroweak penguins and we show that in presence of a new physics contribution their branching ratio can be enhanced by about an order of magnitude, without violating any constraints from other hadronic B decays. This makes them very interesting modes for LHCb and future B factories. In arXiv:1011.6319 we have performed both a model-independent analysis and a study within realistic New Physics models such as a modified-Z^0-penguin scenario, a model with an additional Z' boson and the MSSM. In this article we summarise the most important results of our study.