Dirac spectrum, axial anomaly and the QCD chiral phase transition
The QCD phase transition is studied on 163 and 323 × 4 lattices both with and without quark loops. We introduce a new zero-flavor or quenched species of quark ζ and study the resulting chiral condensate, ζ̄ζ as a function of the ζ mass, mζ. By examining ζ̄ζ for 10-10 ≤ mζ ≤ 10 we gain considerable information about the spectrum of Dirac eigenvalues. A comparison of ma = 0.01 and 0.025 shows little dependence of the Dirac spectrum on such a light, dynamical quark mass, after an overall shift in β is removed. The presence of sufficient small eigenvalues to support anomalous chiral symmetry breaking in the high temperature phase is examined quantitatively. In an effort to enhance these small eigenvalues, ζ̄ζ is also examined in the pure gauge theory in the region of the deconfinement transition with unexpected results. Above the critical temperature, the three Z3 phases show dramatically different chiral behavior. Surprisingly, the real phase shows chiral symmetry, suggesting that a system with one flavor of staggered fermion at Nt = 4 will possess a chiral a phase transition - behavior not expected in the continuum limit.
Chandrasekharan, S; Christ, N
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