Parton distribution of intrinsic charm in two dimensional QCD

TL;DR

This paper investigates the intrinsic charm content in light mesons within two-dimensional QCD, deriving explicit PDFs, comparing models, and analyzing the dependence on charm quark mass.

Contribution

It provides a rigorous calculation of the intrinsic charm PDF in a light meson using the 't Hooft model, linking it to meson cloud and BHPS models.

Findings

Intrinsic charm PDF expressed in terms of 't Hooft wave functions.

The charm quark's average momentum fraction decreases faster than m_c^{-4} with increasing mass.

Quantitative comparison between rigorous results and model predictions.

Abstract

We present a detailed investigation on the intrinsic charm content in a light meson within the 't Hooft model, namely, the two-dimensional QCD in large $N_c$ limit. The intrinsic charm parton distribution function (PDF) of a light meson, which first arises at order $N_c^{-1}$, is explicitly expressed in terms of the 't Hooft wave functions of the light meson and an infinite towers of excited charmed mesons. We also derive the functional forms from the two-dimensional counterparts of the meson cloud model (MCM) and Brodsky-Hoyer-Peterson-Sakai (BHPS) model. We then make a quantitative comparison between our rigorous results and model predictions. We also study how the profile of the intrinsic charm PDF varies with charm quark mass. The average momentum fraction carried by the charm quark inside a light meson is found to decrease faster than $m_c^{-4}$ with increasing charm quark mass.