Abstract

We propose a new formula for the star product in deformation quantization of Poisson structures related in a specific way to a variational problem for a function S, interpreted as the action functional. Our approach is motivated by perturbative algebraic quantum field theory (pAQFT). We provide a direct combinatorial formula for the star product, and we show that it can be applied to a certain class of infinite-dimensional manifolds (e.g. regular observables in pAQFT). This is the first step towards understanding how pAQFT can be formulated such that the only formal parameter is hbar , while the coupling constant can be treated as a number. In the introductory part of the paper, apart from reviewing the framework, we make precise several statements present in the pAQFT literature and recast these in the language of (formal) deformation quantization. Finally, we use our formalism to streamline the proof of perturbative agreement provided by Drago, Hack, and Pinamonti and to generalize some of the results obtained in that work to the case of a nonlinear interaction.

Highlights

  • Constructing interacting quantum field theory (QFT) models in 4 dimensions is one of the most important challenges facing modern theoretical physics

  • We have derived an explicit formula for the deformation quantization of a general class of infinite-dimensional Poisson manifolds

  • We have investigated the relation between our formula and the Kontsevich formula

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Summary

Introduction

Constructing interacting quantum field theory (QFT) models in 4 dimensions is one of the most important challenges facing modern theoretical physics. There, the theory was formulated in terms of formal power series in and the coupling constant λ In this (perturbative) approach, the starting point is an affine configuration space with an action functional that is split into a preferred quadratic (free) part and the remainder. What we achieve here is a construction of the interacting star product that depends only on the full action, the causal structure, and the affine structure of the configuration space This is a desirable result from the pAQFT perspective, since in many situations the split into free and interacting theory is unnatural and the physical results should not depend on this split. We discuss the relation to the formula of Kontsevich, provide some useful formulae for the quantum Møller operator, and we discuss the principle of perturbative agreement

Kinematical structure
The space of field configurations
Functionals on the configuration space
Dynamics
Classical Møller maps off-shell
Deformation quantization
Exponential star products
Quantization maps
Nets of algebras
Time-ordered products
Relation to Weyl quantization
Relation to normal ordering
The Møller operator in the abstract algebra
The Møller operator in terms of functionals
The Møller operator in the time-ordered identification
The naive product
Graphical computations
Noninteracting product
Inverse Møller operator
Composition of operators
Interacting product
Nonperturbative expression for an interacting product
Is there a Kontsevich-type formula?
Interacting Wick product
Formulae for the Møller operators
Perturbative Agreement
Conclusions
Full Text
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