Event-by-event net-charge fluctuations in pp, OO, Ne-Ne, and Pb-Pb collisions with ALICE at the LHC

Abstract

Investigations involving the event-by-event fluctuations of conserved quantities, like net charge, net baryon number, and strangeness in heavy-ion collisions, provide insights into the properties of quark-gluon plasma (QGP) and the phase diagram of strongly interacting matter. Event-by-event fluctuations of net electric charge in pp collisions at $\sqrt{s}=13$ and $13.6$ TeV and for OO, Ne-Ne, and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$ TeV are studied by analysing the data collected by the ALICE detector at CERN Large Hadron Collider. The analysis is carried out in terms of the variable ${\nu }_{\mathrm{dyn}}[+,-]$, chosen for its robustness against detector efficiency losses. The observed dependence of ${\nu }_{\mathrm{dyn}}[+,-]$ on the charged-particle density shows a smooth, energy-independent decrease in the magnitude of ${\nu }_{\mathrm{dyn}}[+,-]$ from smaller to larger collision systems. The negative values of ${\nu }_{\mathrm{dyn}}[+,-]$ indicate a dominance of correlations between oppositely charged particle pairs compared with those arising from like-sign charge pairs. Since ${\nu }_{\mathrm{dyn}}[+,-]$ is known to have an intrinsic dependence on multiplicity, an appropriate scaling is applied. The variable is therefore scaled with the mean multiplicities, $\frac{1}{\frac{1}{⟨N_{+}⟩}+\frac{1}{⟨N_{-}⟩}}$. The dependence of the scaled values of ${\nu }_{\mathrm{dyn}}[+,-]$ on charged particle density is also looked into. The results are compared with model calculations from PYTHIA, EPOS4, AMPT and HIJING.

arXiv comment6 pages, 1 figure. Proceedings of the 14th Edition of the Large Hadron Collider Physics Conference (LHCP2026), Paris, France, 18-22 May 2026. For the ALICE Collaboration