Measuring of chiral susceptibility using gradient flow

In lattice QCD with Wilson-type quarks, the chiral symmetry is explicitly broken by the Wilson term on finite lattices. Though the symmetry is guaranteed to recover in the continuum limit, a series of non-trivial procedures are required to recover the correct renormalized theory in the continuum limit. Recently, a new use of the gradient flow technique was proposed, in which correctly renormalized quantities are evaluated in the vanishing flow-time limit. This enables us to directly study the chiral condensate and its susceptibility with Wilson-type quarks. Extending our previous study of the chiral condensate and its disconnected susceptibility in (2+1)-flavor QCD at a heavy u, d quark mass (m_π /m_ρ ≃ 0.63) and approximately physical s quark mass, we compute the connected contributions to the chiral susceptibility in the temperature range of 178–348 MeV on a fine lattice with a ≃ 0.07 fm.