Charge symmetry violation: a NNLO study of partonic observables

TL;DR

This paper investigates charge symmetry violations in nucleon parton distributions using a meson cloud model and NNLO evolution, highlighting the importance of non-perturbative effects in interpreting experimental anomalies.

Contribution

It introduces an NNLO evolution code for parton distributions including charge symmetry violations and perturbatively generated strange asymmetries, with implications for high-energy experiments.

Findings

Charge symmetry violations are quantified at low resolution scale.

Perturbative strange-antistrange asymmetry is incorporated at three-loop order.

Non-perturbative effects are significant in explaining the NuTeV anomaly.

Abstract

Charge and isospin symmetry violations to valence and sea distribution functions in the nucleon are evaluated (at low resolution scale) by means of a meson cloud model and light-cone quark wave functions. Their perturbative evolution are implemented at Next-to-next-to-leading order (NNLO) using an original evolution code in order to include the perturbatively generated strange - anti-strange asymmetry typical of the three loop evolution expansion. Charge symmetry violating QED effects are also added and the distributions, evolved at the experimental scale, are compared with available information. The role of non-perturbative effects is emphasized in the interpretation of the, so called, NuTeV anomaly and new experiments at very-high energy.