Topological susceptibility in two flavors lattice QCD with the optimal domain-wall fermion

We determine the topological susceptibility of the gauge configurations generated by lattice simulations using two flavors of optimal domain-wall fermion on the 16×32 lattice with length 16 in the fifth dimension, at the lattice spacing a≃0.1 fm. Using the adaptive thick-restart Lanczos algorithm, we project the low-lying eigenmodes of the overlap Dirac operator, and obtain the topological charge of each configuration, for eight ensembles with pion masses in the range 220-550 MeV. From the topological charge, we compute the topological susceptibility and the second normalized cumulant. Our result of the topological susceptibility agrees with the sea-quark mass dependence predicted by the chiral perturbation theory and provides a determination of the chiral condensate, Σ(2 GeV)=[259, and the pion decay constant Fπ=92(12)(2) MeV.