By combining the first unquenched lattice computation of the B-meson binding energy with the recently calculated two-loop contribution to the lattice HQET mass, we determine the MSˉ b-quark mass, mˉb(mˉb) at the NNLO. We find mˉb(mˉb)=(4.26±0.03±0.04±0.05)GeV. The inclusion of the two-loop effects is one of the steps necessary to extract mˉb(mˉb) with a precision better than O(ΛQCD), which is the uncertainty due to the presence of an IR renormalon singularity in the perturbative series of the residual mass. Our results have been obtained on a sample of 60 lattices of size 243×40 at β=5.6, using the unquenched Wilson action with two degenerate sea quarks. The quark propagators have been computed using the unquenched links generated by the TχL Collaboration.
@article{arxiv.hep-lat/9909138,
title = {NNLO unquenched calculation of the b quark mass},
author = {V. Gimenez and L. Giusti and F. Rapuano and G. Martinelli},
journal= {arXiv preprint arXiv:hep-lat/9909138},
year = {2015}
}