scholarly journals On the Symmetries of Quantum Field Theory in Two Dimensions

1992 ◽  
Vol 110 ◽  
pp. 329-335
Author(s):  
Fedor A. Smirnov
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Two Dimensions ◽  
Quantum Field

Quantization and topology: SL(2,R)-de Sitter invariant fields in two dimensions

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040018
Author(s):  
Henri Epstein ◽  
Ugo Moschella
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Two Dimensions ◽  
Quantum Field ◽  
Two Dimensional ◽  
De Sitter ◽  
Cosmological Background ◽  
Local Commutativity ◽  
And Topology ◽  
The Many

We explore the interplay between quantization, local commutativity and the analyticity properties of the two-point functions of a quantum field in a non trivial topological cosmological background in the example of the two-dimensional de Sitter manifold and its double covering. The global topological differences make the many of the well-known features of de Sitter quantum field theory disappear. In particular there is nothing like a Bunch-Davies vacuum and there are no [Formula: see text]-invariant fields whose mass is less than 1/2.

scholarly journals Classical instanton solutions in quantum field theory

2020 ◽  
pp. 78-85
Author(s):  
Roman G. Shulyakovsky ◽  
Alexander S. Gribowsky ◽  
Alexander S. Garkun ◽  
Maxim N. Nevmerzhitsky ◽  
Alexei O. Shaplov ◽  
...  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Quantum Theory ◽  
Yukawa Potential ◽  
Equations Of Motion ◽  
Two Dimensions ◽  
Quantum Field ◽  
Two Dimensional ◽  
Yang Mills ◽  
The One

Instantons are non-trivial solutions of classical Euclidean equations of motion with a finite action. They provide stationary phase points in the path integral for tunnel amplitude between two topologically distinct vacua. It make them useful in many applications of quantum theory, especially for describing the wave function of systems with a degenerate vacua in the framework of the path integrals formalism. Our goal is to introduce the current situation about research on instantons and prepare for experiments. In this paper we give a review of instanton effects in quantum theory. We find in stanton solutions in some quantum mechanical problems, namely, in the problems of the one-dimensional motion of a particle in two-well and periodic potentials. We describe known instantons in quantum field theory that arise, in particular, in the two-dimensional Abelian Higgs model and in SU(2) Yang – Mills gauge fields. We find instanton solutions of two-dimensional scalar field models with sine-Gordon and double-well potentials in a limited spatial volume. We show that accounting of instantons significantly changes the form of the Yukawa potential for the sine-Gordon model in two dimensions.

scholarly journals Topological surprises in de Sitter QFT in two-dimensions

2018 ◽  
Vol 33 (34) ◽  
pp. 1845009 ◽  
Author(s):  
Henri Epstein ◽  
Ugo Moschella
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Thermal State ◽  
Two Dimensions ◽  
Quantum Field ◽  
De Sitter ◽  
Sitter Spacetime ◽  
Klein Gordon ◽  
New Type ◽  
Two Universes

Motivated by the study of soluble models of quantum field theory, we illustrate a new type of topological effect by comparing the constructions of canonical Klein–Gordon quantum fields on the two-dimensional de Sitter spacetime as opposed to its double covering. We show that while the commutators of the two fields coincide locally, the global topological differences make the theories drastically different. Many of the well-known features of de Sitter quantum field theory disappear. In particular, there is nothing like a Bunch–Davies vacuum. Correspondingly, even though the local horizon structure is the same for the two universes, there is no Hawking–Gibbons thermal state. Finally, there is no complementary series of fields.

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