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Entropy and multiplicity of hadrons in the high energy limit within dipole cascade models

Krzysztof Kutak

Sándor Lökös

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Phys. Rev. D 112, 096017 – Published 14 November, 2025

DOI: https://doi.org/10.1103/23wn-66np

Abstract

We investigate and compare quantum chromodynamics (QCD) dipole cascade models, the 1D Mueller dipole model, its high energy limit, and its generalization that follows from studies of 1D systems with conformal symmetry. To address the ambiguity stemming from different definitions of the rapidity ranges in experimental measurements, we propose the entropy as the function of the logarithm of the average multiplicity, S(ln⟨n⟩), as a universal observable. From the solutions of the models, we calculate both the entropy and the average charged particle multiplicity and compare to data measured in proton-proton collisions. We obtained these quantities directly from the measured multiplicity distributions and determine the model parameters via fits. We find that the generalized dipole model provides a significantly better description of the data than the 1D Mueller model.

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Corrections

4 February, 2026

Correction: A grant number in the Acknowledgments was incomplete and has been fixed.

Article Text

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Phys. Rev. D 112, 096017– Published 14 November, 2025
  • Received 16 September 2025
  • Accepted 13 October 2025
  • Corrected 4 February 2026
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