We explore the region of small sea quark masses below mPS/mV=0.5 in two-flavor QCD using a mean-field improved clover quark action and an RG-improved gauge action at a≃0.2 fm on 123×24 and 163×24 lattices. We find that instability of the standard BiCGStab algorithm at small quark masses can be mostly removed by the BiCGStab(DS-L) algorithm, which employs L-th minimal residual polynomials with a dynamical selection of L. We also find singular spikes of ΔH in the HMC algorithm at moderate values of Δτ. Nature of the spike is studied. We also study finite-size effects and chiral properties of meson masses.
@article{arxiv.hep-lat/0209073,
title = {Exploring QCD at small sea quark masses with improved Wilson-type quarks},
author = {PACS Collaboration and Y. Namekawa and S. Aoki and M. Fukugita and K-I. Ishikawa and N. Ishizuka and Y. Iwasaki and K. Kanaya and T. Kaneko and Y. Kuramashi and V. I. Lesk and M. Okawa and Y. Taniguchi and A. Ukawa and T. Umeda and T. Yoshié},
journal= {arXiv preprint arXiv:hep-lat/0209073},
year = {2012}
}