Quenched Chiral Logarithm Diverge in Very Light Quark Region from the Overlap Lattice Quantum Chromodynamics

With an exact chiral symmetry, overlap fermions allow us to reach very light quark region. In the minimum m_ps = 179 MeV, the quenched chiral logarithm diverge is examined. The chiral logarithm parameter δ is calculated from both the pseudo-scalar meson mass m²_ps diverge channel and the pseudo-scalar decay constant f_P channel. In both the cases, we obtain δ = 0.25±0.03. We also observe that the quenched chiral logarithm diverge occurs only in the m_ps ≤ 400 MeV region.