The quark-gluon medium (micro- and macro-QCD)

TL;DR

This paper reviews the properties of the quark-gluon medium in high-energy nucleus collisions, comparing experimental data with theoretical models, and emphasizing its collective behavior and energy loss phenomena.

Contribution

It provides a comprehensive review of microscopic and macroscopic approaches to understanding the quark-gluon medium, highlighting its collective properties and energy loss mechanisms.

Findings

The quark-gluon medium exhibits collective properties.

Partons lose energy when traversing this medium.

Experimental observations align with theoretical models.

Abstract

The properties of the quark-gluon medium observed in high energy nucleus-nucleus collisions are discussed. The main experimental facts about these collisions are briefly described and compared with data about proton-proton collisions. Both microscopic and macroscopic approaches to their description are reviewed. The chromodynamics of the quark-gluon medium at high energies is mainly considered. The energy loss of partons moving in this medium is treated. The principal conclusion is that the medium possesses some collective properties which are crucial for understanding the experimental observations.