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

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  • 25 January 2008
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 24^3x64 lattices (L=1.8 and 2.7 fm) with length 16 in the fifth dimension. The total length of the Monte Carlo trajectory at the lightest quark mass is 7360 units, including 900 for thermalization. We find finite volume effects are larger than the pion mass dependence at the smallest value of m_\pi (= 330 MeV) in our calculation. We also find that g_A exhibits a scaling with the single variable m_\pi L which can also be seen in previous two-flavor domain wall and Wilson fermion calculations. Using this scaling to eliminate the finite-volume effect, we obtain g_A = 1.20(6)(4) at the physical pion mass, m_\pi = 135 MeV, where the first and second errors are statistical and systematic. The observed finite-volume effects also appear in similar quenched simulations, but disappear when V>(2.4$ fm)^3. We argue this is a dynamical quark effect.

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