Nucleon Charges, Form-factors and Neutron EDM

الأصل · EN

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 Nf=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 (Mπ≈ 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 gₐᵘ⁻ᵈ = 1.21(3), gₜᵘ⁻ᵈ = 1.005(59) and gₛᵘ⁻ᵈ = 0.95(12). Further checks of control over all systematic errors, especially in gₐᵘ⁻ᵈ, are still being performed. Using results for the flavor-diagonal charges, gₜᵘ, gₜᵈ and gₜˢ, we analyze contributions of the quark electric dipole moment to the neutron EDM and the consequences for split SUSY model.