Probing anomalous right--handed current in Z b bbar vertex

TL;DR

This paper investigates potential anomalous right-handed couplings in the Z b bbar vertex to explain deviations observed in LEP data, using electroweak precision tests and introducing a new variable for analysis.

Contribution

It introduces a new variable, psilon'_b, to measure anomalous right-handed couplings and explores their implications within contact interactions and left-right models.

Findings

Identifies possible anomalous right-handed Z b bbar couplings.

Analyzes implications for nonuniversal contact interactions.

Considers left-right models as potential explanations.

Abstract

Motivated by $-2 \sigma$ deviation from the Standard Model prediction for the forward--backward asymmetry of $Z \to b \bar{b}$ decay in the LEP data, we explore the anomalous couplings of $Z b \bar{b}$ vertex through the electroweak precision test extended by including $A_{FB}^b$. We introduce a new variable $\epsilon'_b$ to measure the anomalous right-handed coupling in $Z b \bar{b}$ vertex. Implications of our analysis on the nonuniversal contact interactions are studied and the left-right model is also considered as a possible origin of the anomalous right-handed couplings.