This book explains the fundamental concepts and theoretical techniques used to understand the properties of quantum systems having large numbers of degrees of freedom. A number of complimentary approaches are developed, including perturbation theory; nonperturbative approximations based on functional integrals; general arguments based on order parameters, symmetry, and Fermi liquid theory; and stochastic methods.

The series Advances in the Physics of Particles and Nuclei (APPN) is devoted to the archiving, in printed high-quality book format, of the comprehensive, long shelf-life reviews published in The European Physical Journal A and C. APPN will be of benefit in particular to those librarians and research groups, who have chosen to have only electronic access to these journals. Occasionally, original material in review format and refereed by the series' editorial board will also be included. This volume contains the following four reviews: C.E. DeTar and U.M. Heller: QCD Thermodynamics from the Lattice B.R. Holstein: Hadronic Parity violation and Effective Field Theory M. Signore and D. Puy: Cosmic Microwave Background and First Molecules in the Early Universe S. Bethke: The 2009 World Average of alphas

The series Advances in the Physics of Particles and Nuclei (APPN) is devoted to the archiving, in printed high-quality book format, of the comprehensive, long shelf-life reviews published in The European Physical Journal A and C. APPN will be of benefit in particular to those librarians and research groups, who have chosen to have only electronic access to these journals. Occasionally, original material in review format and refereed by the series' editorial board will also be
included.

This volume contains the following two reviews:
Nora Brambilla et al.: Heavy Quarkonium: Progress, Puzzles and Opportunities Daniel Wicke: Properties of the Top Quark

This book explains the fundamental concepts and theoretical techniques used to understand the properties of quantum systems having large numbers of degrees of freedom. A number of complimentary approaches are developed, including perturbation theory; nonperturbative approximations based on functional integrals; general arguments based on order parameters, symmetry and Fermi liquid theory; and stochastic methods. Written for students with no prior background in many-body theory, this text is intended for physicists in solid-state physics, field theory, atomic physics, condensed matter physics, quantum chemistry and nuclear physics.