Undersaturation of quarks at early stages of relativistic nuclear collisions: the hot glue initial scenario and its observable signatures

TL;DR

This paper explores the early stages of high-energy nuclear collisions, proposing a hot gluon-dominated initial state with suppressed quark content, and predicts observable signatures such as reduced high-momentum photon emissions and altered baryon-to-meson ratios.

Contribution

It introduces a novel scenario of chemically undersaturated quark-gluon plasma with time-dependent quark fugacity and provides numerical hydrodynamic results for LHC Pb+Pb collisions.

Findings

Approximately 25% of the total entropy is generated during evolution.

Suppressed high p_T photon and dilepton production predicted.

Reduced baryon to meson ratios expected in early collision stages.

Abstract

The early stage of high multiplicity nuclear collisions is represented by a nearly quarkless, hot, deconfined pure gluon plasma. This new scenario should be characterized by a suppression of high $p_T$ photons and dileptons as well as by reduced baryon to meson ratios. We present the numerical results for central Pb+Pb collisions at the LHC energies by using the ideal Bjorken hydrodynamics with time-dependent quark fugacity. It is shown that about 25\% of final total entropy is generated during the hydrodynamic evolution of chemically undersaturated quark-gluon plasma.