Topological susceptibility in 2+1 flavors lattice QCD with domain-wall fermions

We measure the topological charge and its fluctuation for the gauge configurations generated by the RBC and UKQCD Collaborations using 2 + 1 flavors of domain-wall fermions oil the 163 x 32 lattice (L a, 2 fin) with length 16 in the fifth dimension at the inverse lattice spacing a(-1) similar or equal to 1.62 GeV. From the spectral now of the Hermitian operator H-W(2 + gamma H-5(W))(-1), we obtain the topological charge Q, of each gauge configuration in the three ensembles with light sea quark masses m(q)a = 0.01, 0.02, and 0.03, and with the strange quark mass fixed at m(s)a = 0.04. From Our result of Q(t), we compute the topological Susceptibility X-t = < Q(t)(2)>/Omega, where Omega is the volume of the lattice. In the small m(q) regime. Our result of chi(t) agrees with the chiral effective theory. Using the formula chi(t) = Sigma/(m(u)(-1) + m(d)(-1) + m(s)(-1)) by Leutwyler-Smilga, we obtain the chiral condensate Sigma((MS) over bar)(2 GeV) = 1259(6)(9) MeV vertical bar(3). (C) 2008 Elsevier B.V. All rights reserved.