| dc.description |
By combining the first unquenched lattice computation of the B-meson binding energy and the two-loop contribution to the lattice HQET residual mass, we determine the MSbar b-quark mass, m̅<sub>b</sub>(m̅<sub>b</sub>). The inclusion of the two-loop corrections is essential to extract m̅<sub>b</sub>(m̅<sub>b</sub>) with a precision of O(Λ<sup>2</sup><sub>QCD</sub>/m<sub>b</sub>), which is the uncertainty due to the renormalon singularities in the perturbative series of the residual mass. Our best estimate is m̅<sub>b</sub>(m̅<sub>b</sub>) = (4.26±0.09) GeV, where we have combined the different errors in quadrature. A detailed discussion of the systematic errors contributing to the final number is presented. Our results have been obtained on a sample of 60 lattices of size 24<sup>3</sup> × 40 at β = 5.6, using the Wilson action for light quarks and the lattice HQET for the b quark, at two values of the sea quark masses. The quark propagators have been computed using the unquenched links generated by the TχL collaboration. |
