Axial U(1) symmetry at high temperature in 2-flavor lattice QCD

Abstract

Abstract. We investigate the axial U(1) A symmetry breaking above the critical temperature in two-flavor lattice QCD. The ensembles are generated with dynamical Möbius domain-wall or reweighted overlap fermions. The U(1) A susceptibility is extracted from the low-modes spectrum of the overlap Dirac eigenvalues. We show the quark mass and temperature dependences of U(1) A susceptibility. Our results at T = 220 MeV imply that the U(1) A symmetry is restored in the chiral limit. Its coincidence with vanishing topological susceptibility is observed.

Topological Susceptibility in Nf = 2 QCD at Finite Temperature

“…The preliminary results suggest that for the range of bare mass 0 ≤ m 10 MeV (which includes physical ud mass m 4 MeV) χ t = 0 and for m 10 MeV a sudden development of χ t starts. It is consistent with the prediction of Aoki-Fukaya-Taniguchi [9] with U A (1) symmetry restoration in the chiral limit, thus consistent with the direct measurement of the order parameter of U A (1) [14]. If that were due to finite volume effects and eventually we were to see the breaking in the thermodynamic limit, then Kanazawa-Yamamoto [9] explains how the U A (1) order parameter at finite volume is related to χ t .…”

Axial U(1) symmetry, topology, and Dirac spectra at high temperature in Nf=2 lattice QCD

“…In these proceedings, in order to examine the U(1) A symmetry in the high-temperature phase above T c , we show the results of the U(1) A susceptibility, topological susceptibility, and corresponding Dirac spectra from N f = 2 lattice QCD simulations, where finer lattice spacing, 1/a = 2.64 GeV (a ∼ 0.075 fm), than the previous works [1,4] is used. Note that a part of the results has also been reported in previous proceedings [26,27,28].…”

Axial U(1) symmetry and mesonic correlators at high temperature in $N_f=2$ lattice QCD

“…The physical quark mass (as the average of up and down quark masses) is estimated to be am = 0.0014(2) (3.7(5) MeV). Some of our results were already reported in previous proceedings [18,19,20,21].…”