High-precision determination of the electric and magnetic form factors of the proton

TL;DR

This study provides highly precise measurements of the proton's electric and magnetic form factors through elastic electron-proton scattering, revealing features at the pion cloud scale and accurately determining the proton radii.

Contribution

It presents new high-precision measurements of proton form factors and radii, utilizing extensive data and model fits to improve understanding of proton structure.

Findings

Form factors show features at the pion cloud scale

Charge radius r_E=0.879 fm, magnetic radius r_M=0.777 fm

Statistical and systematic errors are minimized and well quantified

Abstract

New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q^2=1 (GeV/c)^2 with statistical errors below 0.2%. The electric and magnetic form factors of the proton were extracted by fits of a large variety of form factor models directly to the cross sections. The form factors show some features at the scale of the pion cloud. The charge and magnetic radii are determined to be r_E=0.879(5)(stat.)(4)(syst.)(2)(model)(4)(group) fm and r_M=0.777(13)(stat.)(9)(syst.)(5)(model)(2)(group) fm.