The Study of the contribution of the LHT model to $Zb\bar{b}$ coupling

TL;DR

This paper investigates how the Littlest Higgs Model with T-parity (LHT) affects Z-b-bbar couplings at one-loop level, analyzing implications for observable quantities like R_b and A_FB^b, and constraining model parameters with experimental data.

Contribution

It provides a detailed one-loop analysis of LHT contributions to Zbar{b} couplings and assesses their impact on R_b and A_FB^b, offering constraints on model parameters.

Findings

LHT mainly affects left-handed Zbar{b} coupling.

Small parameter space can reduce deviation from experimental data.

Precision R_b measurements impose strong constraints.

Abstract

In the framework of the Littlest Higgs Model with T-parity (LHT), we study the contributions of the new particles to $Zb\bar{b}$ couplings at one-loop level. Based on these results, we further study the branching ratio $R_{b}$ and the unpolarized forward-backward asymmetry ${A_{FB}^{b}}$. We find that the correction of the new particles to $Zb\bar{b}$ couplings is mainly on the left-handed coupling and has small part of the parameter space to alleviate the deviation between theoretical predictions and experimental values. The precision measurement value of $R_{b}$ can give severe constraints on the relevant parameters. The constraints from the precision measurement value of ${A_{FB}^{b}}$ are very weak.