This is an introductory review of the physics of quantum spin liquid states. Quantum
magnetism is a rapidly evolving field, and recent developments reveal that the ground states …

The renormalization group plays an essential role in many areas of physics, both
conceptually and as a practical tool to determine the long-distance low-energy properties of …

NATURE abounds with phase transitions. The boiling and freezing of water are everyday
examples of phase transitions, as are more exotic processes such as superconductivity and …

The general properties of the factorized S-matrix in two-dimensional space-time are
considered. The relation between the factorization property of the scattering theory and the …

This volume links field theory methods and concepts from particle physics with those in
critical phenomena and statistical mechanics, the development starting from the latter point …

We review results concerning the critical behavior of spin systems at equilibrium. We
consider the Ising and the general O (N)-symmetric universality classes, including the N→ 0 …

The classical planar Heisenberg model is studied at low temperatures by means of
renormalization theory and a series of exact transformations. A numerical study of the Migdal …

We review the use of an exact renormalization group equation in quantum field theory and
statistical physics. It describes the dependence of the free energy on an infrared cutoff for the …

It is argued that the long-wavelength, low-temperature behavior of a two-dimensional
quantum Heisenberg antiferromagnet can be described by a quantum nonlinear σ model in …

The spin-½ antiferromagnetic Heisenberg model on a square lattice is used to describe the
dynamics of the spin degrees of freedom of undoped copper oxides. Even though the model …