Maximally entangled proton and charged hadron multiplicity in Deep Inelastic Scattering

TL;DR

This paper investigates the entanglement entropy in Deep Inelastic Scattering using parton distribution functions, comparing theoretical predictions with experimental data, and explores entropy behavior at lower photon virtualities with non-linear QCD effects.

Contribution

It provides a detailed comparison of entanglement entropy calculations with experimental data and explores the impact of different PDFs and QCD evolution methods.

Findings

Good agreement with H1 data within uncertainties

Uncertainties due to normalization and hadron multiplicity relations

Predictions for entropy at lower photon virtualities

Abstract

We study the proposal by Kharzeev-Levin to determine entanglement entropy in Deep Inelastic Scattering (DIS) from parton distribution functions (PDFs) and to relate the former to the entropy of final state hadrons. We find several uncertainties in the current comparison to data, in particular the overall normalization, the relation between charged versus total hadron multiplicity in the comparison to experimental results as well as different methods to determine the number of partons in Deep Inelastic Scattering. We further provide a comparison to data based on leading order HERA PDF as well as PDFs obtained from an unintegrated gluon distribution subject to next-to-leading order Balitsky-Fadin-Kuraev-Lipatov and Balitsky-Kovchegov evolution. Within uncertainties we find good agreement with H1 data. We provide also predictions for entropy at lower photon virtualities, where non-linear QCD dynamics is expected to become relevant.