Action physics

A Track Physics Model of Radiation Action

A model of radiation action by energetic heavy ions, inspired by a study of particle tracks in electron sensitive emulsion, has been successfully applied to many radiation effects in condensed matter, yielding quantitative descriptions and occasional predictions. Radiation effects are attributed primarily to secondary electrons. Each detector is imagined to be a collection of targets whose radi...

Laser physics: Quantum controversy in action

Hamiltonian and Action Principle Formulations of Plasma Physics

Hamiltonian and action principle formulations of the basic equations of plasma physics are reviewed. Various types of Lagrangian and Poisson bracket formulations for kinetic and fluid theories are discussed, and it is described how such formulations can be used to derive and approximate physical models. Additional uses are also described. Two applications are treated in greater detail: an algor...

Supergravity , the DBI Action and Black Hole Physics

The assumptions behind the recently conjectured relation between gauge theory and supergravity are elaborated on. It is pointed out that the scaling limit that preserves supergravity solutions, gives the entire DBI action on the gauge theory side, but in the low energy limit the relation between the conformal field theory and Anti-de Sitter supergravity emerges. We also argue that recent work o...

Effective Average Action in Statistical Physics and Quantum Field Theory

An exact renormalization group equation describes the dependence of the free energy on an infrared cutoff for the quantum or thermal fluctuations. It interpolates between the microphysical laws and the complex macroscopic phenomena. We present a simple unified description of critical phenomena for O(N)-symmetric scalar models in two, three or four dimensions, including essential scaling for the...