Work

Kinematic and dynamical origins of mean-p fluctuations in heavy-ion collisions

Year: 2026

Type: article

Abstract: Event-by-event fluctuations of the mean transverse momentum (mean- p T ) provide a sensitive probe of collective dynamics beyond single-particle spectra and anisotropic flow. We present a systematic study of mean- p T fluctuation observables using a Bayesian-calibrated multistage hydrodynamic framework, including quantitative comparisons to RHIC measurements and model-based investigations of beam-energy and kinematic-acceptance effects. The experimental definitions employed by the STAR and ALICE Collaborations are implemented explicitly and found to yield consistent results within controlled limits. We study the centrality and beam-energy dependence of the observable, its sensitivity to key soft-sector ingredients, and the impact of the kinematic p T acceptance. By introducing scaled- p T cuts, we demonstrate that a part of the apparent energy dependence arises from kinematic projection effects, while the remaining trends reflect genuine collective dynamics. Our results establish mean- p T fluctuations as a nontrivial and independent validation of calibrated hydrodynamic descriptions of the quark–gluon plasma.

Source: Physics Letters B

DOI: 10.1016/j.physletb.2026.140225

Author: Lipei Du

Institutions: Lawrence Berkeley National Laboratory, University of California, Berkeley

Language: English

Topic: High-Energy Particle Collisions Research

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond

Funders: U.S. Department of Energy, University of Washington, Office of Science, Nuclear Physics

Awards: INSTITUTE FOR NUCLEAR THEORY, G2821925151