Probing QGP using local charge fluctuations in heavy-ion collisions

¹ Department of Physics, University of Houston, Houston, TX 77204, USA
² Nuclear Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
³ Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine

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Published online: 17 April 2026

Abstract

We revisit the D-measure of event-by-event net-electric charge fluctuations, an idea first introduced over 20 years ago as a potential signature for the presence of quark-gluon plasma (QGP) in heavy-ion collisions. We developed a quantitative framework that incorporates resonance-decay effects, global and local charge conservation, and experimental kinematic cuts. Folding these effects into a formalism of density correlations yields an improved expression for the D-measure inside acceptance. We make comparisons with ALICE data for Pb-Pb collisions at √s_NN = 2.76 TeV. We find that a hadron-gas scenario can describe the data only for a very short charge conservation range, while a QGP scenario is in good agreement with the measurement and is relatively insensitive to the charge conservation range. A Bayesian comparison of both scenarios shows moderate evidence for freeze-out of charge fluctuations in the QGP phase.