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

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 $Zb\bar{b}$ vertex through the electroweak precision test extended by including $A_{FB}^b$. We introduce a new variable ${ϵ}_b^{\prime }$ to measure the anomalous right-handed coupling in $Zb\bar{b}$ 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.

Comments: use elsart.sty, 11 pages, 5 .eps figures included