Charged Particle and Photon Multiplicity, and Transverse Energy Production in High-Energy Heavy-Ion Collisions

TL;DR

This paper reviews experimental results on charged particle, photon multiplicity, and transverse energy production in high-energy heavy-ion collisions, discussing models and physics insights into the quark-gluon plasma formation and collision dynamics.

Contribution

It provides a comprehensive synthesis of data and models on multiplicity and energy production across energies, highlighting the physics of the deconfined phase in heavy-ion collisions.

Findings

Charged particle and photon multiplicities increase with energy and centrality.

Initial energy density estimates suggest conditions suitable for quark-gluon plasma formation.

Transverse energy per particle relates to chemical freeze-out conditions.

Abstract

We review the charged particle and photon multiplicity, and transverse energy production in heavy-ion collisions starting from few GeV to TeV energies. The experimental results of pseudorapidity distribution of charged particles and photons at different collision energies and centralities are discussed. We also discuss the hypothesis of limiting fragmentation and expansion dynamics using the Landau hydrodynamics and the underlying physics. Meanwhile, we present the estimation of initial energy density multiplied with formation time as a function of different collision energies and centralities. In the end, the transverse energy per charged particle in connection with the chemical freeze-out criteria is discussed. We invoke various models and phenomenological arguments to interpret and characterize the fireball created in heavy-ion collisions. This review overall provides a scope to understand the heavy-ion collision data and a possible formation of a deconfined phase of partons via the global observables like charged particles, photons and the transverse energy measurement.