# Nucleon spin structure functions at NNLO in the presence of target mass corrections and higher twist effects

## TL;DR

This paper extracts polarized parton distribution functions at NNLO, incorporating target mass corrections and higher-twist effects, to improve understanding of nucleon spin structure using recent polarized structure function data.

## Contribution

It provides a new set of polarized PDFs called KTA17, including nonperturbative corrections and a detailed uncertainty analysis at NNLO in QCD.

## Key findings

- PPDFs are stable and reliable with target mass and higher-twist corrections.
- Sum rules are validated and compared with existing literature.
- Uncertainties are realistically estimated using Hessian error propagation.

## Abstract

We extract polarized parton distribution functions (PPDFs), referred to as "KTA17," together with the highly correlated strong coupling $\alpha_s$ from recent and up-to-date $g_1$ and $g_2$ polarized structure functions world data at next-to-next-to-leading order in perturbative QCD. The stability and reliability of the results are ensured by including nonperturbative target mass corrections as well as higher-twist terms which are particularly important at the large-$x$ region at low Q$^2$. Their role in extracting the PPDFs in the nucleon is studied. Sum rules are discussed and compared with other results from the literature. This analysis is made by means of the Jacobi polynomials expansion technique to the DGLAP evolution. The uncertainties on the observables and on the PPDFs throughout this paper are computed using standard Hessian error propagation which served to provide a more realistic estimate of the PPDFs uncertainties.