Rare B decays and Tevatron top-pair asymmetry

TL;DR

This paper explores the connection between the Tevatron top quark forward-backward asymmetry anomaly and rare B decays, analyzing a model with a new charged gauge boson and its implications for B decay observables.

Contribution

It demonstrates the correlation between top asymmetry mechanisms involving $t$- or $u$-channel processes and rare B decay measurements, particularly in a $W'$ model.

Findings

The $B^- o ext{pi}^- ar{K}^0$ decay is most affected by new physics effects.

Allowed parameter space is constrained by current B decay measurements at 2σ level.

New physics has negligible impact on direct CP asymmetry in B decays.

Abstract

The recent Tevatron result on the top quark forward-backward asymmetry, which deviates from its standard model prediction by 3.4$\sigma$, has prompted many authors to build new models to account for this anomaly. Among the various proposals, we find that those mechanisms which produce $t\bar t$ via $t$- or $u$-channel can have a strong correlation to the rare B decays. We demonstrate this link by studying a model with a new charged gauge boson, $W'$. In terms of the current measurements on $B\to \pi K$ decays, we conclude that the branching ratio for $B^-\to \pi^- \bar K^0$ is affected most by the new effects. Furthermore, using the world average branching ratio for the exclusive B decays at $2\sigma$ level, we discuss the allowed values for the new parameters. Finally, we point out that the influence of the new physics effects on the direct CP asymmetry in B decays is insignificant.