Study of Collective Phenomena in Heavy-Ion Collisions Using CMS Open Data

TL;DR

This paper presents preliminary measurements of a new observable, $v_0(p_T)$, in lead-lead collisions using CMS open data, revealing features of collective radial flow consistent with previous ATLAS results, thus probing quark-gluon plasma dynamics.

Contribution

It introduces the measurement of the $v_0(p_T)$ observable in PbPb collisions using open data, providing new insights into radial flow fluctuations in the quark-gluon plasma.

Findings

Observation of long-range correlations in pseudorapidity

Shape of $v_0(p_T)$ is centrality-independent

Results are compatible with ATLAS measurements at higher energy

Abstract

In this work, we present preliminary results from a measurement of the recently proposed observable, $v_0(p_T)$, in lead-lead (PbPb) collisions at $\sqrt{s_{NN}}=2.76 \text{ TeV}$, using public data from the CMS Open Data portal. This observable is directly sensitive to radial flow and characterizes the transverse momentum ($p_T$) dependence of radial flow fluctuations, serving as probe of collective phenomena in the quark-gluon plasma (QGP) formed in heavy-ion collisions. Consistently with the ATLAS results at $\sqrt{s_{NN}}=5.02 \text{ TeV}$, we observe the three key features of collective radial flow: long-range correlations in pseudorapidity ($\eta$), a centrality-independent shape as a function of $p_T$, and factorization in $p_T$. The results presented in this work are generally compatible, within uncertainties, with the ATLAS measurements at $\sqrt{s_{NN}}=5.02\text{ TeV}$ reported in Phys. Rev. Lett. 136, 032301 (2026).