2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/38867We study the $B^0_s-\bar{B^0_s}$ mixing amplitude in Standard Model by computing the relevant hadronic matrix element in the static limit of lattice HQET with the Neuberger light quark action. In the quenched approximation, and after matching to the $\bar{\rm MS}$ scheme in QCD, we obtain $\hat{B}^{\bar{\rm MS},{\rm NLO}}_{B_s}(m_b)=0.940(16)(22)$.talk given at the Electroweak session of Moriond 2005High Energy Physics - LatticeHigh Energy Physics - Phenomenologytext