Quenched and first unquenched lattice HQET determination of the Bs-Meson width difference

TL;DR

This paper reports lattice QCD calculations of the Bs meson lifetime difference using both quenched and unquenched simulations, including next-to-leading order corrections and two-loop anomalous dimensions.

Contribution

It provides the first unquenched lattice QCD determination of the Bs lifetime difference with next-to-leading order accuracy.

Findings

Quenched result: (5.1 ± 1.9 ± 1.7)×10^(-2)

Unquenched result: (4.3 ± 2.0 ± 1.9)×10^(-2)

Includes two-loop anomalous dimensions and matching calculations.

Abstract

We present recent results for the prediction of the Bs lifetime difference from lattice Heavy Quark Effective Theory simulations. In order to get a next-to-leading order result we have calculated the matching between QCD and HQET and the two-loop anomalous dimensions in the HQET for all the \Delta B=2 operators, in particular for the operators which enter the width difference. We present results from quenched and, for the first time, from unquenched simulations. We obtain for the Bs lifetime difference, (\Delta\Gamma_Bs/\Gamma_Bs)^{(que.)}=(5.1+/- 1.9+/- 1.7)10^(-2) and (\Delta\Gamma_Bs/\Gamma_Bs)^{(unq.)}=(4.3+/- 2.0+/- 1.9)10^(-2) from the quenched and unquenched simulations respectively