Variational Approach to the Calculation of gA
  We present a lattice QCD calculation of the nucleon axial charge, gA, using a variational approach. After a brief outline of how the variational method is applied to the calculation of form factors, we present results for gA using this method. We find that ground state dominance is rapid, evident in the early onset of a clear plateau in the correlation function ratio proportional to gA. Through a comparison with results obtained via traditional methods, we show how excited state effects can suppress gA by as much as 8% if sources are not properly tuned. 
Benjamin J. Owen, Jack Dragos, Waseem Kamleh, Derek B. Leinweber, M.   Selim Mahbub, Benjamin J. Menadue, James M. Zanotti
hep-lat