Intrinsic Charm Parton Distribution Functions from CTEQ-TEA Global Analysis

TL;DR

This paper investigates the presence of intrinsic charm in the proton's parton distribution functions using a global analysis with three different models, comparing their fits to experimental data and exploring correlations with the charm quark mass.

Contribution

It introduces and compares three models for intrinsic charm in the proton within a NNLO global analysis, providing insights into their compatibility with experimental data.

Findings

Intrinsic charm models can be fitted to data with varying degrees of support.

Correlations between charm quark mass and intrinsic charm content are identified.

The analysis constrains the possible magnitude and shape of intrinsic charm in the proton.

Abstract

We study the possibility of intrinsic (non-perturbative) charm in parton distribution functions (PDF) of the proton, within the context of the CT10 next-to-next-to-leading order (NNLO) global analysis. Three models for the intrinsic charm (IC) quark content are compared: (i) $\hat{c}(x) = 0$ (zero-IC model); (ii) $\hat{c}(x)$ is parametrized by a valence-like parton distribution (BHPS model); (iii) $\hat{c}(x)$ is parametrized by a sea-like parton distribution (SEA model). In these models, the intrinsic charm content, $\hat{c}(x)$, is included in the charm PDF at the matching scale $Q_c=m_c=1.3$ GeV. The best fits to data are constructed and compared. Correlations between the value of $m_c$ and the amount of IC are also considered.