Bottom-Quark Forward-Backward Asymmetry in the Standard Model and Beyond

TL;DR

This paper calculates the bottom-quark forward-backward asymmetry at the Tevatron within the Standard Model and various new physics models, highlighting how light new physics can significantly alter the asymmetry and aid in distinguishing NP explanations of the top asymmetry.

Contribution

It provides a detailed computation of bottom-quark asymmetry in the SM and explores how light new physics scenarios can cause measurable deviations.

Findings

SM bottom asymmetry dominated by electroweak at Z-pole

QCD effects dominate above Z-pole

Light new physics can significantly alter the asymmetry

Abstract

We computed the bottom-quark forward-backward asymmetry at the Tevatron in the Standard Model and for several new physics scenarios. Near the $Z$-pole, the SM bottom asymmetry is dominated by tree level exchanges of electroweak gauge bosons. While above the $Z$-pole, next-to-leading order QCD dominates the SM asymmetry as was the case with the top quark forward-backward asymmetry. Light new physics, $M_{NP} \precsim 150$ GeV, can cause significant deviations from the SM prediction for the bottom asymmetry. The bottom asymmetry can be used to distinguish between competing NP explanations of the top asymmetry based on how the NP interferes with s-channel gluon and $Z$ exchange.