Chiral extrapolation of nucleon magnetic form factors

Abstract

The extrapolation of nucleon magnetic form factors calculated within lattice QCD is investigated within a framework based upon heavy baryon chiral effective-field theory. All one-loop graphs are considered at arbitrary momentum transfer and all octet and decuplet baryons are included in the intermediate states. Finite range regularisation is applied to improve the convergence in the quark-mass expansion. At each value of the momentum transfer ($Q^2$), a separate extrapolation to the physical pion mass is carried out as a function of $m_\pi$ alone. Because of the large values of $Q^2$ involved, the role of the pion form factor in the standard pion-loop integrals is also investigated. The resulting values of the form factors at the physical pion mass are compared with experimental data as a function of $Q^2$ and demonstrate the utility and accuracy of the chiral extrapolation methods presented herein.