Next-to-Leading-Order QCD Predictions for the Nucleon Form Factors

TL;DR

This paper presents the first next-to-leading-order QCD calculations of nucleon Dirac form factors, revealing significant one-loop corrections and providing a comprehensive analysis aligned with experimental data.

Contribution

It introduces the first NLO QCD predictions for nucleon form factors using rigorous factorization, including soft contributions, enabling robust extraction of nucleon distribution amplitudes.

Findings

One-loop corrections are numerically significant across accessible momentum transfers.

The analysis aligns theoretical predictions closely with experimental measurements.

Soft Feynman mechanism contributions are essential for accurate form factor modeling.

Abstract

We accomplish for the first time the next-to-leading-order QCD computations of the leading-twist contributions to the Dirac form factors of both the proton and the neutron by applying the hard-collinear factorization theorem rigorously. The resulting predictions for these baryon form factors indicate that the one-loop perturbative corrections to the hard-gluon-exchange contributions are numerically substantial for a wide range of momentum transfers accessible in the current and forthcoming collider experiments. Including further the (formally) power-suppressed soft contributions due to the celebrated Feynman mechanism, we then perform the state-of-the-art analysis of the Dirac electromagnetic nucleon form factors from first field-theoretical principles, thus allowing for the most robust determinations of the nucleon distribution amplitudes from the direct comparison with the experimental measurements.