Jul 26 – 30, 2021
US/Eastern timezone

Nucleon-pion-state contamination in lattice computations of the nucleon electromagnetic form factors

Jul 27, 2021, 6:45 AM
15m
Oral presentation Hadron Structure Hadron Structure

Speaker

Dr Oliver Baer (Humboldt University Berlin, Germany)

Description

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 $G_{\rm E}(Q^2)$ 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 $G_{\rm M}(Q^2)$ 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.

Primary authors

Dr Oliver Baer (Humboldt University Berlin, Germany) Mr Haris Colic (Humboldt University Berlin)

Presentation materials