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Main Authors: Rabelo-Soares, Gabriel, Francener, Reinaldo, Ramos, Gabriel S., Torrieri, Giorgio
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2512.24855
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author Rabelo-Soares, Gabriel
Francener, Reinaldo
Ramos, Gabriel S.
Torrieri, Giorgio
author_facet Rabelo-Soares, Gabriel
Francener, Reinaldo
Ramos, Gabriel S.
Torrieri, Giorgio
contents Recent studies have shown that hadronic multiplicity in deep inelastic scattering can be associated with entanglement entropy. However, such definitions are intrinsically longitudinal and do not capture the full phase-space structure of the proton. In this work, we investigate the proton Wehrl entropy constructed from the gluon Husimi distribution, which provides a positive phase-space description within the present definitions and model calculations. Within this framework, we employ a gluon light-front spectator model based on soft-wall AdS/QCD-inspired wave functions, with free parameters constrained by global NNPDF fits, allowing us to compute both parton distribution functions and Wigner distributions. The Husimi distribution is obtained via Gaussian smearing of the Wigner distribution with width given by the saturation scale in the GBW model. We show that from a normalized Husimi distribution one can decompose the Wehrl entropy into an entanglement entropy term and a residual term associated with transverse degrees of freedom. Numerical results for the proton entanglement entropy are shown and compared with CMS data, while the Wehrl entropy is presented for different values of the virtuality.
format Preprint
id arxiv_https___arxiv_org_abs_2512_24855
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle QCD Wehrl and entanglement entropies in a gluon spectator model at small-$x$
Rabelo-Soares, Gabriel
Francener, Reinaldo
Ramos, Gabriel S.
Torrieri, Giorgio
High Energy Physics - Phenomenology
Nuclear Theory
Recent studies have shown that hadronic multiplicity in deep inelastic scattering can be associated with entanglement entropy. However, such definitions are intrinsically longitudinal and do not capture the full phase-space structure of the proton. In this work, we investigate the proton Wehrl entropy constructed from the gluon Husimi distribution, which provides a positive phase-space description within the present definitions and model calculations. Within this framework, we employ a gluon light-front spectator model based on soft-wall AdS/QCD-inspired wave functions, with free parameters constrained by global NNPDF fits, allowing us to compute both parton distribution functions and Wigner distributions. The Husimi distribution is obtained via Gaussian smearing of the Wigner distribution with width given by the saturation scale in the GBW model. We show that from a normalized Husimi distribution one can decompose the Wehrl entropy into an entanglement entropy term and a residual term associated with transverse degrees of freedom. Numerical results for the proton entanglement entropy are shown and compared with CMS data, while the Wehrl entropy is presented for different values of the virtuality.
title QCD Wehrl and entanglement entropies in a gluon spectator model at small-$x$
topic High Energy Physics - Phenomenology
Nuclear Theory
url https://arxiv.org/abs/2512.24855