Lattice measurement of $B_{B_s}$ with a chiral light quark action

TL;DR

This paper presents a lattice QCD calculation of the $B_{B_s}$ bag parameter using a chiral light quark action, combining HQET static limit and Neuberger fermions, resulting in a precise estimate relevant for $B_s$ mixing.

Contribution

It introduces a novel lattice computation of $B_{B_s}$ using a chiral symmetric light quark action combined with HQET static limit, improving accuracy.

Findings

Estimated $B_{B_s}$ in $ar{MS}$ scheme: 0.92(3)

Method preserves chiral symmetry on the lattice

Combines HQET static limit with Neuberger action

Abstract

The computation on the lattice of the bag parameter $B_{B_s}$ associated to the $B_s - \bar{B_s}$ mixing amplitude in the Standard Model is presented. The estimation has been made by combining the static limit of HQET and the Neuberger light quark action which preserves the chiral symmetry on the lattice. We find $B^{\bar{MS}}{stat}}_{B_s}(m_b)=0.92(3)$.