A QCD Analysis of Double Parton Scattering: Color Correlations, Interference Effects and Evolution

TL;DR

This paper develops a theoretical framework for double parton scattering in QCD, including color correlations and interference effects, and analyzes their evolution and suppression at high energies.

Contribution

It introduces a factorization formula for double Drell-Yan processes incorporating color, spin, and interference effects, with a detailed study of their evolution and suppression.

Findings

Color correlations are Sudakov suppressed at high energies.

The evolution of double parton distribution functions involves both UV and rapidity divergences.

Soft radiation effects are non-perturbative and described by soft functions.

Abstract

We derive a factorization formula for the double Drell-Yan cross section in terms of double parton distribution functions (dPDFs). Diparton flavor, spin and color correlations and parton-exchange interference terms contribute, even for unpolarized beams. Soft radiation effects are nontrivial for the color correlation and interference contributions, and are described by non-perturbative soft functions. We provide a field-theoretic definition of the quark dPDFs and study some of their basic properties, including discrete symmetries and their interpretation in a non-relativistic quark model. We calculate the renormalization group evolution of the quark dPDFs and of the soft functions. The evolution receives contributions from both ultraviolet and rapidity divergences. We find that color correlation and interference effects are Sudakov suppressed, greatly reducing the number of dPDFs needed to describe double parton scattering at high energy experiments.