nLab separating vector (changes)

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**algebraic quantum field theory

Context

Functional analysis

AQFT

algebraic quantum field theory (perturbative, on curved spacetimes, homotopical)

Introduction

Concepts

field theory:

Lagrangian field theory

quantization

quantum mechanical system, quantum probability

free field quantization

gauge theories

interacting field quantization

renormalization

Theorems

States and observables

Operator algebra

Local QFT

Perturbative QFT

** (perturbative, on curved spacetimes, homotopical) Introduction ## Concepts **field theory**: * classical, pre-quantum, quantum, perturbative quantum * relativistic, Euclidean, thermal **Lagrangian field theory** * field (physics) * field bundle * field history * space of field histories * Lagrangian density * Euler-Lagrange form, presymplectic current * Euler-Lagrange equations of motion * locally variational field theory * covariant phase space * Peierls-Poisson bracket * advanced and retarded propagator, * causal propagator **quantization** * geometric quantization of symplectic groupoids * algebraic deformation quantization, star algebra **quantum mechanical system**, **quantum probability** * subsystem * observables * field observables * local observables * polynomial observables * microcausal observables * operator algebra, C*-algebra, von Neumann algebra * local net of observables * causal locality * Haag-Kastler axioms * Wightman axioms * field net * conformal net * state on a star-algebra, expectation value * pure state wave function collapse of the wave function/conditional expectation value * mixed state, density matrix * space of quantum states * vacuum state * quasi-free state, * Hadamard state * Wightman propagator * picture of quantum mechanics **free field quantization** * star algebra, Moyal deformation quantization * Wick algebra * canonical commutation relations, Weyl relations * normal ordered product * Fock space **gauge theories** * gauge symmetry * BRST complex, BV-BRST formalism * local BV-BRST complex * BV-operator * quantum master equation * master Ward identity * gauge anomaly **interacting field quantization** * causal perturbation theory, perturbative AQFT * interaction * S-matrix, scattering amplitude * causal additivity * time-ordered product, Feynman propagator * Feynman diagram, Feynman perturbation series * effective action * vacuum stability * interacting field algebra * Bogoliubov's formula * quantum Møller operator * adiabatic limit * infrared divergence * interacting vacuum **renormalization** * ("re-")normalization scheme * extension of distributions * ("re"-)normalization condition * quantum anomaly * renormalization group * interaction vertex redefinition * Stückelberg-Petermann renormalization group * renormalization group flow/running coupling constants * effective quantum field theory * UV cutoff * counterterms * relative effective action * Wilsonian RG, Polchinski flow equation ## Theorems {#Theorems} ### States and observables * order-theoretic structure in quantum mechanics * Alfsen-Shultz theorem * Harding-Döring-Hamhalter theorem * Kochen-Specker theorem * Bell's theorem * Fell's theorem * Gleason's theorem * Wigner theorem * Bub-Clifton theorem * Kadison-Singer problem ### Operator algebra * Wick's theorem * GNS construction * cyclic vector, separating vector * modular theory * Fell's theorem * Stone-von Neumann theorem * Haag's theorem ### Local QFT * Reeh-Schlieder theorem * Bisognano-Wichmann theorem * PCT theorem * spin-statistics theorem * DHR superselection theory * Osterwalder-Schrader theorem (Wick rotation) ### Perturbative QFT * Schwinger-Dyson equation * main theorem of perturbative renormalization

Contents

Definition

Let ℳ\mathcal{M} be a von Neumann algebra acting on a Hilbert space ℋ\mathcal{H}.

A vector x∈ℋx \in \mathcal{H} is a separating vector if M(x)=0M(x) = 0 implies M=0M = 0 for all M∈ℳM \in \mathcal{M}.

Properties

The notions of separating vector is dual to that of cyclic vector with respect to the commutant ℳ′\mathcal{M}', that is a vector is cyclic for ℳ\mathcal{M} iff it is separating for ℳ′\mathcal{M}'.

Applications

In the context of AQFT separating vectors appear as vacuum states . See Reeh-Schlieder theorem.

Last revised on November 30, 2010 at 11:43:54. See the history of this page for a list of all contributions to it.