Topological susceptibility in ( 2 + 1 ) - flavor lattice QCD with overlap fermion

We determine the topological susceptibility χ t in the topologically-trivial sector generated by lattice simulations of N f = 2 + 1 QCD with overlap Dirac fermion, on a 16 3 × 48 lattice with lattice spacing ∼ 0.11 fm, for five sea quark masses m q ranging from m s /6 to m s (where m s is the physical strange quark mass). The χ 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 m q regime, our result of χ t agrees with the chiral effective theory. Using the formula χ t = Σ(m −1 u + m −1 d + m −1 s) −1 by Leutwyler-Smilga, we obtain the chiral condensate Σ MS (2 GeV) = [253(4)(6)MeV] 3. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.