List of Symbols viiPreface xiii Part 1. De Sitter Space Chapter 1. De Sitter Space as a Lorentzian Manifold 1.1. The metric and the isometry group 1.2. The causal structure 1.3. Geodesics and geodesic distances 1.4. Wedges and double cones 1.5. Finite speed of propagation Chapter 2. Space-time symmetries 2.1. The group O(1, 2) 2.2. Horospheres 2.3. The complex Lorentz group 2.4. The Cartan decomposition of SO 0 (1, 2) 2.5. The Iwasawa decomposition of SO 0 (1, 2) 2.6. The Hannabuss decomposition of SO 0 (1, 2) 2.7. Homogeneous spaces, cosets and orbits 2.8. Invariant measures Part 2. Harmonic Analysis Chapter 3. Induced Representations for the Lorentz Group 3.1. The general case 3.2. Induced representations for SO 0 (1, 2) 3.3. Unitary representations on a circle on the light cone 3.4. Unitary representations on the mass shell Chapter 4. Harmonic Analysis on the Hyperboloid 4.1. Tuboids 4.2. Plane waves 4.3. The Fourier-Helgason transformation 4.4. The Plancherel theorem on the hyperboloid iii iv CONTENTS Part 3. Classical Fields Chapter 5. Classical Field Theory 5.1. The classical equations of motion 5.2. Conservation Laws 5.3. The covariant classical dynamical system 5.4. The restriction of the KG equation to a (double) wedge 5.5. The canonical classical dynamical system Part 4. Free Quantum Fields Chapter 6. One-Particle Hilbert Spaces 6.1. The covariant one-particle Hilbert space 6.2. The canonical one-particle Hilbert space 6.3. Time-symmetric and time-antisymmetric test-functions Chapter 7. Quantum One-Particle Structures 7.1. The covariant one-particle structure 7.2. One-particle structures with positive and negative energy 7.3. One-particle KMS structures 7.4. The canonical one-particle structure Chapter 8. Second Quantization 8.1. De Sitter vacuum states 8.2. The canonical free field 8.3. Analyticity properties of the correlation functions Part 5. Euclidean Quantum Fields Chapter 9. The Euclidean Sphere 9.1. The symmetry group of the sphere 9.2. Geographical and path-space coordinates Chapter 10. Gaussian Measures 10.1. The definition of the measure 10.2. Properties of the covariance 10.3. Sobolev spaces 10.4. Conditional expectations 10.5. Sharp-time fields 10.6. Foliation of the Euclidean field Chapter 11. Non-Gaussian Measures 11.1. Wick ordering of random variables 11.2. Sharp-time interactions 11.3. Foliations of the interaction Part 6. The Osterwalder-Schrader Reconstruction Chapter 12. The Reconstruction of Free Quantum Fields CONTENTS v 12.1. Reflection positivity 12.2. The reconstruction of the Hilbert space 12.3. Generalised path spaces 12.4. Path-spaces on the sphere 12.5. Local symmetric semigroups 12.6. Tomita-Takesaki modular theory 12.7. Multi-analyticity of the correlation functions 12.8. The interacting vacuum vector Chapter 13. The Reconstruction of Interacting Quantum Fields 13.1. The Hilbert space for the interacting measure 13.2. Virtual representations 13.3. A unitary representation of the Lorentz group 13.4. Perturbation theory of generalised path spaces Part 7. Interacting Quantum...