Abstract and subjects
We present an update of our analysis of statistical and systematic errors in the calculation of iso-vector scalar, axial and tensor charges of the nucleon. The calculations are done using \(N_f=2+1+1\) flavor HISQ ensembles generated by the MILC Collaboration at three values of the lattice spacing (\(a=0.12,\ 0.09,\) and \(0.06\) fm) and three values of the quark mass (\(M_\pi \approx 310,\ 220\) and \(130\) MeV); and clover fermions for calculating the correlation functions, i.e., we use a clover-on-HISQ lattice formulation. The all-mode-averaging method allows us to increase the statistics by a factor of eight for the same computational cost leading to a better understanding of and control over excited state contamination. Our current results, after extrapolation to the continuum limit and physical pion mass are \(g_A^{u-d} = 1.21(3)\), \(g_T^{u-d} = 1.005(59)\) and \(g_S^{u-d} = 0.95(12) \). Further checks of control over all systematic errors, especially in \(g_A^{u-d}\), are still being performed. Using results for the flavor-diagonal charges, \(g_T^{u} \), \(g_T^{d} \) and \(g_T^{s}\), we analyze contributions of the quark electric dipole moment to the neutron EDM and the consequences for split SUSY model.