Quantum entanglement correlations in double quark PDFs

TL;DR

This paper applies Quantum Information Theory to analyze quantum entanglement in double quark parton distribution functions, revealing significant non-classical correlations at higher energy scales through a novel non-perturbative model and QCD evolution.

Contribution

It introduces a new approach combining quantum information measures with QCD evolution to study entanglement in double quark PDFs, providing first qualitative numerical results.

Findings

Non-classical correlations are significant at small and asymmetric momentum fractions.

Quantum entanglement persists and becomes manifest at higher Q^2 scales.

First numerical insights into the scale evolution of quantum correlations in double PDFs.

Abstract

Methods from Quantum Information Theory are used to scrutinize quantum correlations encoded in the two-quark density matrix over light-cone momentum fractions $x_1$ and $x_2$. A non-perturbative three quark model light-cone wavefunction predicts significant non-classical correlations associated with the "entanglement negativity" measure for asymmetric and small quark momentum fractions. We perform one step of QCD scale evolution of the entire density matrix, not just its diagonal (dPDF), by computing collinearly divergent corrections due to the emission of a gluon. Finally, we present first qualitative numerical results for single-step scale evolution of quantum entanglement correlations in double quark PDFs. At a higher $Q^2$ scale, the non-classical correlations manifest in the dPDF for nearly symmetric momentum fractions.