The Chirality of $b$ Quark Couplings

TL;DR

This paper reviews the chirality of $b$ quark weak couplings, exploring theoretical models and phenomenological implications, and suggests experimental methods to measure the $b$ to $c$ current's chirality.

Contribution

It introduces a model with purely right-handed $b$-decay couplings consistent with current experiments and proposes new experimental approaches to determine the chirality of these couplings.

Findings

The model aligns with recent $B$ decay measurements.

Parity asymmetries in $ ext{Lambda}_b$ decays can reveal chirality.

Right-handed couplings could significantly affect $b$ decay phenomenology.

Abstract

This review addresses the question of the chirality of $b$ quark weak couplings from a theoretical and from a purely phenomenological point of view. Due to their small magnitude $b$ decay couplings are subject to possible large corrections from right-handed terms, on the one hand, and do not affect the weak interactions of the first two quark families in any observable manner, on the other hand. This motivated an $SU(2)_L\times SU(2)_R\times U(1)$ model with purely right-handed $b$-decay couplings. The model is consistent with experiments, including recent measurements of a lepton forward-backward asymmetry in $B\to D^*\ell\nu$ and of radiative $B$ decays. Parity violating asymmetries in semileptonic decays of polarized $\Lambda_b$ baryons produced in $Z^0$ decays provide a promising way of measuring the chirality of the $b$ to $c$ current.