Model for Polarized and Unpolarized Parton Density Functions in the Nucleon

TL;DR

This paper introduces a unified physical model for polarized and unpolarized parton density functions of the nucleon, accurately fitting a wide range of experimental data without assuming charge symmetry.

Contribution

It presents the first proton and neutron PDFs that do not rely on charge symmetry assumptions, unifying the description of polarized and unpolarized structure functions.

Findings

Successfully reproduces experimental structure function data across various Q^2 ranges.

Provides proton and neutron PDFs without charge symmetry assumptions.

Achieves a unified explanation for polarized and unpolarized data.

Abstract

We present a physical model for polarized and unpolarized structure functions and parton density functions (PDFs) of the proton and the neutron. It reproduces the data on F_2^p(x,Q^2) for 0.00001<x<1 and 2.5<Q^2<5000 GeV^2, F_2^p(x)-F_2^n(x), F_2^n(x)/F_2^p(x), xg(x), dbar(x)-ubar(x), d(x)/u(x), the Gottfried sum, the fractional momentum of charged partons and the polarized structure functions g_1^{p,n}(x), at various Q^2. We present for the first time, proton and neutron PDFs which do not assume charge symmetry. Contrary to the common practice, we explain polarized and unpolarized data with a single model.