Topological susceptibility in (2+1)-flavor lattice QCD with overlap fermion
Abstract
We determine the topological susceptibility t in the topologically-trivial sector generated by lattice simulations of Nf = 2+1 QCD with overlap Dirac fermion, on a 163 x 48 lattice with lattice spacing ~ 0.11 fm, for five sea quark masses mq ranging from ms/6 to ms (where ms is the physical strange quark mass). The t is extracted from the plateau (at large time separation) of the 2-point and 4-point time-correlation functions of the flavor-singlet pseudoscalar meson η', which arises from the finite size effect due to fixed topology. In the small mq regime, our result of t agrees with the chiral effective theory. Using the formula t = (mu-1 + md-1 + ms-1)-1 by Leutwyler-Smilga, we obtain the chiral condensate MSbar(2 GeV) = [249(4)(2) MeV]3.