Now in paperback, this text introduces the theoretical framework for describing the quark-gluon plasma, an important new state of matter. The first part of this book is a self-contained introduction to relativistic thermal field theroy. Topics include the path integral approach, the real and imaginary-time formalisms, fermion fields and gauge fielda at finite temperature. Useful techniquess such as the evaluation of frequency sums or the use of cutting rules are illustrated in various examples.

The second part of the book is devoted to recent developments, giving a detailed accunt of collective excitations (bosonic and fermionic), and showing how they give rise to energy scales which imply a reorganization of perturbation theory. The relation with kinetic is also explained.

Appoications to processes which occur in heavy ion collisions and in astrophysics are worked out in detail. Each cahpter ends with exercises and a guide to the literature

The Book will be of interest to theoreticians working elementary paricle physics, nuclear physics and astrophysics.

1. Introduction
2. Quantum Statistical Mechanics
3. The Scalar field at fintie etmperature
4. Simple applications of perturbation theory
5. Dirac and Gauge fields at finite temperature
6. Collective excitations in a plasma
7. Hard thermal loops and resummation
8. Dynamical screening
9. Neutrino ecission from stars
10. Infrared prolems at finite temperature

A. Formulary
B. Operator Formalism