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Nucleon axial charge in 2+1 flavor dynamical lattice QCD with domain wall fermions

T. Yamazaki, Y. Aoki, T. Blum, H. W. Lin, M. F. Lin, S. Ohta, S. Sasaki, R. J. Tweedie, J. M. Zanotti

TL;DR

The observed finite-volume scaling also appears in similar quenched simulations, but disappear when V>or=(2.4 fm);{3}.

Abstract

We present results for the nucleon axial charge g_A at a fixed lattice spacing of 1/a=1.73(3) GeV using 2+1 flavors of domain wall fermions on size 16^3x32 and 24^3x64lattices (L=1.8 and 2.7 fm) with length 16 in the fifth dimension. The length of the Monte Carlo trajectory at the lightest m_πis 7360 units, including 900 for thermalization. We find finite volume effects are larger than the pion mass dependence at m_π= 330 MeV. We also find that g_A exhibits a scaling with the single variable m_πL which can also be seen in previous two-flavor domain wall and Wilson fermion calculati ons. Using this scaling to eliminate the finite-volume effect, we obtain g_A = 1.20(6)(4) at the physical pion mass, m_π= 135 MeV, where the first and second errors are statistical and systematic. The observed finite-volume scaling also appears in similar quenched simulations, but disappear when V\ge (2.4 fm)^3. We argue this is a dynamical quark effect.

Nucleon axial charge in 2+1 flavor dynamical lattice QCD with domain wall fermions

TL;DR

The observed finite-volume scaling also appears in similar quenched simulations, but disappear when V>or=(2.4 fm);{3}.

Abstract

We present results for the nucleon axial charge g_A at a fixed lattice spacing of 1/a=1.73(3) GeV using 2+1 flavors of domain wall fermions on size 16^3x32 and 24^3x64lattices (L=1.8 and 2.7 fm) with length 16 in the fifth dimension. The length of the Monte Carlo trajectory at the lightest m_πis 7360 units, including 900 for thermalization. We find finite volume effects are larger than the pion mass dependence at m_π= 330 MeV. We also find that g_A exhibits a scaling with the single variable m_πL which can also be seen in previous two-flavor domain wall and Wilson fermion calculati ons. Using this scaling to eliminate the finite-volume effect, we obtain g_A = 1.20(6)(4) at the physical pion mass, m_π= 135 MeV, where the first and second errors are statistical and systematic. The observed finite-volume scaling also appears in similar quenched simulations, but disappear when V\ge (2.4 fm)^3. We argue this is a dynamical quark effect.

Paper Structure

This paper contains 3 figures, 1 table.

Figures (3)

  • Figure 1: Plateaus of $g_A$. $V=(2.7$ fm$)^3$ and $m_f = 0.005$, 0.01, 0.02, and 0.03, from top to bottom.
  • Figure 2: $g_A$. Dashed and solid lines denote the fit results and chiral extrapolation in infinite volume, respectively. The open circle is extrapolated result at $m_\pi = 135$ MeV.
  • Figure 3: $m_\pi L$ scaling of $g_A$. Top, middle, and bottom panels are dynamical and mixed action DWF, dynamical Wilson, and quenched DWF results, respectively. In bottom panel, open symbol is same as in top panel.