The gluon and charm content of the deuteron

TL;DR

This paper calculates the gluon and charm parton-distribution functions of the deuteron using light-front quantization and realistic nuclear forces, revealing small differences from the proton and potential intrinsic charm enhancements.

Contribution

It introduces a frame-independent method to evaluate gluon and charm PDFs of the deuteron with realistic nuclear wave functions, including intrinsic charm effects.

Findings

Gluon distribution per nucleon is slightly smaller than in the proton at intermediate x.

Gluon distribution is strongly enhanced for x > 0.6.

Intrinsic charm in the deuteron may be significantly increased due to hidden-color configurations.

Abstract

We evaluate the frame-independent gluon and charm parton-distribution functions (PDFs) of the deuteron utilizing light-front quantization and the impulse approximation. We use a nuclear wave function obtained from solving the nonrelativistic Schroedinger equation with the realistic Argonne v18 nuclear force, which we fold with the proton PDF. The predicted gluon distribution in the deuteron (per nucleon) is a few percent smaller than that of the proton in the domain x_{bj} = Q^2 / (2 p_N \cdot q) \sim 0.4, whereas it is strongly enhanced for x_{bj} larger than 0.6. We discuss the applicability of our analysis and comment on how to extend it to the kinematic limit x_{bj} \to 2. We also analyze the charm distribution of the deuteron within the same approach by considering both the perturbatively and non-perturbatively generated (intrinsic) charm contributions. In particular, we note that the intrinsic-charm content in the deuteron will be enhanced due to 6-quark "hidden-color" QCD configurations.