Evidence for the maximally entangled low $x$ proton in Deep Inelastic Scattering from H1 data

TL;DR

This paper tests the hypothesis of a maximally entangled proton wave function at low x in Deep Inelastic Scattering, using H1 data and advanced parton distribution functions, finding good agreement with the theoretical model.

Contribution

It introduces a novel approach to determine partonic entropy from gluon and quark distributions and compares different PDF frameworks against experimental data.

Findings

Good agreement between the entanglement-based model and H1 data

Next-to-next-to-leading order with small x resummation describes data acceptably

Partonic entropy can be effectively estimated from unintegrated gluon distributions

Abstract

We investigate the proposal by Kharzeev and Levin of a maximally entangled proton wave function in Deep Inelastic Scattering at low $x$ and the proposed relation between parton number and final state hadron multiplicity. Contrary to the original formulation we determine partonic entropy from the sum of gluon and quark distribution functions at low $x$, which we obtain from an unintegrated gluon distribution subject to next-to-leading order Balitsky-Fadin-Kuraev-Lipatov evolution. We find for this framework very good agreement with H1 data. We furthermore provide a comparison based on NNPDF parton distribution functions at both next-to-next-to-leading order and next-to-next-to-leading with small $x$ resummation, where the latter provides an acceptable description of data.