Mass of the b-quark and B-decay constants from Nf=2+1+1 twisted-mass Lattice QCD

TL;DR

This paper reports precise lattice QCD calculations of the b-quark mass, quark mass ratios, and B-meson decay constants using configurations with four dynamical quark flavors, extrapolated to physical conditions.

Contribution

It introduces a new high-precision determination of b-quark parameters and B-decay constants using Nf=2+1+1 twisted-mass lattice QCD with multiple lattice spacings and pion masses.

Findings

b-quark mass mb(MSbar, mb) = 4.26(10) GeV

ratio mb/mc = 4.42(8)

decay constant fBs = 229(5) MeV

Abstract

We present precise lattice computations for the b-quark mass, the quark mass ratios mb/mc and mb/ms as well as the leptonic B-decay constants. We employ gauge configurations with four dynamical quark flavors, up/down, strange and charm, at three values of the lattice spacing (a ~ 0.06 - 0.09 fm) and for pion masses as low as 210 MeV. Interpolation in the heavy quark mass to the bottom quark point is performed using ratios of physical quantities computed at nearby quark masses exploiting the fact that these ratios are exactly known in the static quark mass limit. Our results are also extrapolated to the physical pion mass and to the continuum limit and read: mb(MSbar, mb) = 4.26(10) GeV, mb/mc = 4.42(8), mb/ms = 51.4(1.4), fBs = 229(5) MeV, fB = 193(6) MeV, fBs/fB = 1.184(25) and (fBs/fB)/(fK/fpi) = 0.997(17).