Topological susceptibility in two-flavor lattice QCD with exact chiral symmetry

Understand

We determine the topological susceptibility $\chi_t$ in two-flavor QCD using the lattice simulations at a fixed topological sector.

• The topological charge density is unambiguously defined on the lattice using the overlap-Dirac operator which possesses exact chiral symmetry.
• Simulations are performed on a $16^3 \times 32$ lattice at lattice spacing $\sim$ 0.12 fm at six sea quark masses $m_q$ ranging in $m_s/6$--$m_s$ with $m_s$ the physical strange quark mass.
• The $\chi_t$ is extracted from the constant behavior of the time-correlation of flavor-singlet pseudo-scalar meson two-point function at large distances, which arises from the finite size effect due to the fixed topology.