Indications for freeze-out of charge fluctuations in the quark-gluon plasma at the LHC

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Hauptverfasser: Parra, Jonathan, Poberezhniuk, Roman, Koch, Volker, Ratti, Claudia, Vovchenko, Volodymyr
Format: Preprint
Veröffentlicht: 2025
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author Parra, Jonathan
Poberezhniuk, Roman
Koch, Volker
Ratti, Claudia
Vovchenko, Volodymyr
author_facet Parra, Jonathan
Poberezhniuk, Roman
Koch, Volker
Ratti, Claudia
Vovchenko, Volodymyr
contents The D-measure of net-charge fluctuations quantifies the variance of net charge in strongly interacting matter. It was introduced over 20 years ago as a potential signal of quark-gluon plasma (QGP) in heavy-ion collisions, where it is expected to be suppressed due to the fractional electric charges of quarks. Measurements have been performed at RHIC and LHC, but the conclusion has been elusive in the absence of quantitative calculations for both scenarios. We address this issue by employing a recently developed formalism of density correlations and incorporate resonance decays, local charge conservation, and experimental kinematic cuts. We find that the hadron gas scenario is in fair agreement with the ALICE data for $\sqrt{s_{\rm NN}} = 2.76$ TeV Pb-Pb collisions only when a very short rapidity range of local charge conservation is enforced, while the QGP scenario is in excellent agreement with experimental data and largely insensitive to the range of local charge conservation. A Bayesian analysis of the data utilizing different priors yields moderate evidence for the freeze-out of charge fluctuations in the QGP phase relative to hadron gas. The upcoming high-fidelity measurements from LHC Run 2 will serve as a precision test of the two scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2504_02085
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Indications for freeze-out of charge fluctuations in the quark-gluon plasma at the LHC
Parra, Jonathan
Poberezhniuk, Roman
Koch, Volker
Ratti, Claudia
Vovchenko, Volodymyr
High Energy Physics - Phenomenology
Nuclear Experiment
Nuclear Theory
The D-measure of net-charge fluctuations quantifies the variance of net charge in strongly interacting matter. It was introduced over 20 years ago as a potential signal of quark-gluon plasma (QGP) in heavy-ion collisions, where it is expected to be suppressed due to the fractional electric charges of quarks. Measurements have been performed at RHIC and LHC, but the conclusion has been elusive in the absence of quantitative calculations for both scenarios. We address this issue by employing a recently developed formalism of density correlations and incorporate resonance decays, local charge conservation, and experimental kinematic cuts. We find that the hadron gas scenario is in fair agreement with the ALICE data for $\sqrt{s_{\rm NN}} = 2.76$ TeV Pb-Pb collisions only when a very short rapidity range of local charge conservation is enforced, while the QGP scenario is in excellent agreement with experimental data and largely insensitive to the range of local charge conservation. A Bayesian analysis of the data utilizing different priors yields moderate evidence for the freeze-out of charge fluctuations in the QGP phase relative to hadron gas. The upcoming high-fidelity measurements from LHC Run 2 will serve as a precision test of the two scenarios.
title Indications for freeze-out of charge fluctuations in the quark-gluon plasma at the LHC
topic High Energy Physics - Phenomenology
Nuclear Experiment
Nuclear Theory
url https://arxiv.org/abs/2504.02085