Nucleon Axial and Electromagnetic Form Factors

Abstract

We present results for the isovector axial, induced pseudoscalar, electric, and magnetic form factors of the nucleon. The calculations were done using $2+1+1$-flavor HISQ ensembles generated by the MILC collaboration with lattice spacings $a\approx$ 0.12, 0.09, 0.06$\mathrm{fm}$ and pion masses $M_{\pi }\approx$ 310, 220, 130$\mathrm{MeV}$. Excited-states contamination is controlled by using four-state fits to two-point correlators and by comparing two- versus three-states in three-point correlators. The $Q^2$ behavior is analyzed using the model independent z-expansion and the dipole ansatz. Final results for the charge radii and magnetic moment are obtained using a simultaneous fit in $M_{\pi }$, lattice spacing $a$ and finite volume.

Comments: 8 pages, 5 figures, Lattice 2017 - 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spain