This volume contains papers based on talks delivered at the Third Workshop on Quantum Field Theory under the /nftuence of External Conditions held at the University of Leipzig from September 18th to September 22nd, 1995. This series of Workshops is organized by the quantum field theory group at the University of Leipzig. The first and the second Workshop in the row have been held in 1989 and 1992. The present meeting has been joined by more than 70 participants. This fact underlines the vivid interest in the field covered by the Workshop ranging from the Casimir effect to semiclassical gravity. The material of this volume is organized along five subjects. The first part is devoted to the Casimir effect itself. The actual interest is mostly in non-stationary boundaries and a possible explanation of the phenomenon of sonoluminescence - a still open and challenging question. The second part deals with QED and QCD in external fields. The main interest was focused on the effective action approach, on some aspects of the bag model and on quantum effects in a conical background. The ground state in external fields is studied in the contributions of the third part. They demonstrate that the zeta function regularization tagether with the heat kerne! expansion is the most powerful method at present. New calculations of functional determinants, of finite temperature effects and an interesting method applicable in the presence of smooth background fields are presented.

Table of Contents:
Casimir Energy for a Spherical Cavity in a Dielectric: Toward a Model for Sonoluminescence?.- Conformal Invariance with Boundaries.- Hard, Semihard and Soft Boundary Conditions.- Quantum Radiation from Mirrors Moving Sideways.- Sonoluminescence as Quantum Vacuum Radiation.- Dynamical Casimir Effect, “Particle Emission” and Squeezing.- Photon Generation and Squeezing in a Cavity with Vibrating Walls.- Fluctuations of the Casimir Pressure at Finite Temperature.- Casimir Theory for the Piecewise Uniform String.- Casimir Force Between Real Boundaries: Contributions of Mechanical and Electrical Imperfections.- Renormalization Group Flow of the Chern-Simons Parameter.- The Effective Lagrangian of Arbitrary Inhomogeneous Electromagnetic Field.- Gauge Theories in a Bag.- Instantons in the Bag Model: Matrix Elements of Scalar Propagator.- QED in the External Aharonov-Bohm Field.- Quantum Fields in a Conical Background.- Magnetic Response of the Many-Particle Chern-Simons Gauge Theory in (2+1) Dimensions.- Self-Interaction Force for Charged Particle in the Space-Time of Supermassive Cosmic String.- Exact Euler-Heisenberg Effective Action for Chiral Fermions in Some Special External Fields.- Energy-Momentum Tensor of Particles Created by an External Field.- Nonlocality, Self-Adjointness of the Hamiltonian and Vacuum Polarization in Spaces with Nontrivial Topology.- Hydrogen Atom in the Spacetime of a Cosmic String.- Functional Determinants on Möbius Corners.- Applications of Zeta Function Regularization in QFT.- Ground State Energy in Smooth Background Fields.- Quantum Field Theory at Finite Temperature and Cosmological Perturbations.- Algorithms for the Calculation of the Heat Kernel Coefficients.- Finite Temperature Field Theory: Physical Effects of Nontrivial SpectralFunctions.- Bose-Einstein Condensation under External Conditions.- Speed of Light in Nontrivial Vacua.- Influence of Condensates and External Fields on Physical Effects in Gauge Theories.- Effective Potential in Yang-Mills Theory and Stability of Chromomagnetic Vacuum.- Ground State Energy Density in Smooth Background Fields.- Black Hole Entropy.- Thermodynamic Features of Black Holes Dressed with Quantum Fields.- Thermodynamics in D-dimensional Rindler-like Spaces.- On the Quantum Stability of the Time Machine.- Field Interaction Effects of a Charged String in a Magnetic Background.- A Selfconsistent Semiclassical Solution with a Wormhole in the Theory of Gravity.- General Quantization Anomaly in Bosonic String Theory Interacting with Background Gravitational Field.- Non-Local Properties in Euclidean Quantum Gravity.- Geroch—Kinnersley—Chitre Group for Dilaton—Axion Gravity.- Geometric Quantization of Kähler Spaces Admitting H-Projective Mappings.- Renormalization Group and Effective Action in Renormalizable Quantum Gravity with Matter.- Phase Structure of 2D Gross-Neveu Model in Spacetimes of Constant Curvature.- Spinning Particles in Taub-NUT Background.- Quantum Optics of Accelerated 2-level Systems on Arbitrary Stationary Trajectories.- Radiation-Field Quantization for Linear Dielectrics through Green’s Function Expansion.- Localization of Electromagnetic Waves in two Dimensions.- Spontaneous Emission by Atoms near a Dielectric Waveguide.- The Vacuum of (QED)0+1 and Functional Integral Measure with Boundary Conditions.- VI Appendix.- Program of the Workshop.- List of Participants.