Decay constant of B_s and B^*_s mesons from mathrm{N_f}=2 lattice QCD

Rahul Balasubramamian,Benoît Blossier

doi:10.1140/epjc/s10052-020-7965-z

Abstract

We report on a two-flavor lattice QCD estimate of the B_s and B^*_s leptonic decays parameterized by the decay constants f_{B_s} and f_{B^*_s}. In addition to their relevance for phenomenology, their extraction has allowed us to investigate whether the “step scaling in mass” strategy is suitable with Wilson–Clover fermions to smoothly extrapolate quantities of the heavy-strange sector up to the bottom scale. From the central value of f_{D_s} quoted by FLAG at N_f=2 and our ratio frac{f_{B_s}}{f_{D_s}}, we obtain f_{B_s}=215(10)(2)(^{+2}_{-5}) MeV and f_{B^*_s}/f_{B_s}=1.02(2)(^{+2}_{-0}).

Highlights

In the very active research of new effects in high-energy particle physics, flavour physics does play a key role at the so-called intensity frontier
Rare events are sensitive probes of New Physics (NP) scenarios with the exchange of extra particles in quantum loops with respect to what is known from the Standard Model (SM), theoretical uncertainties on hadronic quantities, for instance hadron decay constants, that encode the dynamics of QCD at large distance, severely weaken the constraints that are derived through the analysis of experimental data
In that paper we have reported on a lattice estimate of fBs and f Bs∗ / fBs

Summary

Introduction

In the very active research of new effects in high-energy particle physics, flavour physics does play a key role at the so-called intensity frontier. Rare events are sensitive probes of New Physics (NP) scenarios with the exchange of extra particles in quantum loops with respect to what is known from the Standard Model (SM), theoretical uncertainties on hadronic quantities, for instance hadron decay constants, that encode the dynamics of QCD at large distance, severely weaken the constraints that are derived through the analysis of experimental data. Those hadronic constants cannot be reliably estimated in perturbation theory.

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