We calculate the light meson spectrum and the light quark masses by lattice QCD simulation, treating all light quarks dynamically and employing the Iwasaki gluon action and the nonperturbatively O(a)-improved Wilson quark action. The calculations are made at the squared lattice spacings at an equal distance a^2~0.005, 0.01 and 0.015 fm^2, and the continuum limit is taken assuming an O(a^2) discretization error. The light meson spectrum is consistent with experiment. The up, down and strange quark masses in the \bar{MS} scheme at 2 GeV are \bar{m}=(m_{u}+m_{d})/2=3.55^{+0.65}_{-0.28} MeV and m_s=90.1^{+17.2}_{-6.1} MeV where the error includes statistical and all systematic errors added in quadrature. These values contain the previous estimates obtained with the dynamical u and d quarks within the error.
@article{arxiv.0704.1937,
title = {Light quark masses from unquenched lattice QCD},
author = {JLQCD Collaboration and T. Ishikawa and S. Aoki and M. Fukugita and S. Hashimoto and K-I. Ishikawa and N. Ishizuka and Y. Iwasaki and K. Kanaya and T. Kaneko and Y. Kuramashi and M. Okawa and Y. Taniguchi and N. Tsutsui and A. Ukawa and N. Yamada and T. Yoshié},
journal= {arXiv preprint arXiv:0704.1937},
year = {2012}
}
Comments
4 pages, 3 figures, revtex4; v2: contents partly modified, published version