Top Quark Forward-Backward Asymmetry and Anomalous Right-Handed Charge Currents

TL;DR

This paper explores how new physics related to top quark asymmetry and flavor-changing couplings can generate right-handed charge currents, potentially resolving discrepancies in |V_{ub}| measurements while avoiding strict experimental bounds.

Contribution

It demonstrates that flavor-changing couplings can naturally produce anomalous right-handed charge currents, addressing tensions in |V_{ub}| determinations and evading indirect constraints.

Findings

Flavor-changing couplings generate loop-induced right-handed charge currents.

These currents can reconcile |V_{ub}| measurements.

The model avoids tight bounds from B → X_s γ.

Abstract

Recent measurements of the top quark forward-backward asymmetry at the Tevatron could hint at new physics with an unexpected flavor structure. The significance of such an abnormal flavor structure in alleviating the tension between the various determinations of $|V_{ub}|$ via right-handed charge currents is studied. In particular, we elaborate on how the associated new flavor changing couplings naturally allow for the generation of anomalous loop-induced right-handed charge currents which can simultaneously remove the tension in the determinations of $|V_{ub}|$ and escape the tight indirect bounds from $B \ra X_s \gamma$.