$N\pi$-state contamination in lattice calculations of the nucleon electromagnetic form factors

Abstract

The nucleon-pion-state contribution to QCD two-point and three-point functions relevant for lattice calculations of the nucleon electromagnetic form factors are studied in chiral perturbation theory. To leading order the results depend on a few experimentally known low-energy constants only, and the nucleon-pion-state contribution to the form factors can be estimated. The nucleon-pion-state contribution to the electric form factor $G_{\mathrm{E}}(Q^2)$ is at the +5 percent level for a source-sink separation of 2 fm, and it increases with increasing momentum transfer $Q^2$. For the magnetic form factor the nucleon-pion-state contribution leads to an underestimation of $G_{\mathrm{M}}(Q^2)$ by about 5 percent that decreases with increasing $Q^2$. For smaller source-sink separations that are accessible in present-day lattice simulations the impact is larger, although the ChPT results may not be applicable for such small time separations. Still, a comparison with lattice data at $t\approx 1.6$ fm works reasonably well.

33 pages, 11 figures

References in corpus (10)

• Model independent extraction of the proton charge radius from electron scattering
• $N\pi$-state contamination in lattice calculations of the nucleon axial form factors
• Isovector electromagnetic form factors of the nucleon from lattice QCD and the proton radius puzzle
• A local factorization of the fermion determinant in lattice QCD
• Chiral Corrections to Nucleon Two- and Three-Point Correlation Functions
• Time Dependence of Nucleon Correlation Functions in Chiral Perturbation Theory
• Chiral perturbation theory and nucleon-pion-state contaminations in lattice QCD
• $N\pi$-states and the projection method for the nucleon axial and pseudoscalar form factors
• Excited states in nucleon structure calculations
• Nucleon-pion-state contribution in lattice calculations of moments of parton distribution functions

Cited by in corpus (5)

• The pion-nucleon sigma term from lattice QCD
• Nucleon relativistic polarization and magnetization distributions
• Investigation of pion-nucleon contributions to nucleon matrix elements
• Application of Laplace filters to the analysis of lattice time correlators
• Proton and neutron electromagnetic form factors from lattice QCD in the continuum limit