A chiral SU(4) explanation of the $b\to s$ anomalies

TL;DR

This paper introduces a chiral SU(4) Pati-Salam model that unifies quarks and leptons to explain B-meson decay anomalies, making testable predictions for future collider experiments.

Contribution

It presents a novel chiral SU(4) extension of the Pati-Salam model that accounts for lepton flavor universality violation in B decays.

Findings

Model explains deviations in B meson decays

Satisfies current experimental constraints

Predicts observable effects at LHCb and Belle II

Abstract

We propose a variant of the Pati-Salam model, with gauge group $SU(4)_C\times SU(2)_L\times U(1)_{Y'}$, in which the chiral left-handed quarks and leptons are unified into a $\underline{4}$ of $SU(4)_C$, while the right-handed quarks and leptons have quite a distinct treatment. The $SU(4)_C$ leptoquark gauge bosons can explain the measured deviation of lepton flavour universality in the rare decays: $\bar B \to \bar K^{(*)}\bar\ell\ell, \ell=\mu,e$ (taken as a hint of new physics). The model satisfies the relevant experimental constraints and makes predictions for the important $B$ and $\tau$ decays. These predictions will be tested at the LHCb and Belle II experiments when increased statistics become available.