- Toward Quantum Fields: Scalar and Spinor Fields

2013 ◽  
pp. 164-177
Keyword(s):  
Quantum Fields ◽  
Spinor Fields

The scattering matrix and the Green functions

2021 ◽  
pp. 99-116
Author(s):  
Iosif L. Buchbinder ◽  
Ilya L. Shapiro
Keyword(s):  
Scattering Matrix ◽  
Quantum Scattering ◽  
Green Functions ◽  
Particle Interactions ◽  
Quantum Fields ◽  
Spinor Fields ◽  
Quantized Fields

In this chapter, the book begins to develop a perturbative formalism to describe the interactions of quantized fields and, in particular, the interactions of particles in terms of their quantum fields. Quantum scattering requires the description of particle interactions and asymptotic states, which are introduced in detail. The n-point Green functions are defined. An essential part of the chapter is devoted to deriving the reduction of the S-matrix in terms of the Green functions. The compact description of these notions is achieved by introducing the generating functionals of Green functions and the S-matrix. The same constructions are also introduced for the spinor fields.

scholarly journals Elimination of Primitive Divergents from Field Theory by Means of Complex Coupling Constants

1973 ◽  
Vol 26 (6) ◽  
pp. 703
Author(s):  
AF Nicholson
Keyword(s):  
Field Theory ◽  
Matrix Element ◽  
Spinor Field ◽  
Scalar Fields ◽  
Coupling Constants ◽  
Quantum Fields ◽  
Iteration Theory ◽  
Spinor Fields ◽  
S Matrix ◽  
Physical Particle

LSZ. iteration theory is extended to accommodate quantum fields coupled by complex constants, while retaining a positive metric and a Hermitian Hamiltonian. Interpolating and particle (~in, out) fields are linked by an operator U(t) which is nonunitary, so that Haag's theorem may be avoided. It is shown that U(t) may be rendered sufficiently well-behaved as t -+ � 00 to allow development of the iteration series for the T function. For certain combinations of fields the coupling constants and masses can then be chosen so as to eliminate the primitive divergents from the iteration series for any S-matrix element. The theory is illustrated by two models: four spinor plus two scalar fields, and the electromagnetic plus several spinor fields. In the second model not every spinor field corresponds to a stable physical particle, and the LSZ formalism is extended to allow for this.

scholarly journals THE GENERAL-COVARIANT AND GAUGE-INVARIANT THEORY OF QUANTUM PARTICLES IN CLASSICAL BACKGROUNDS

2003 ◽  
Vol 12 (03) ◽  
pp. 407-444 ◽  
Author(s):  
HRVOJE NIKOLIĆ
Keyword(s):  
Particle Production ◽  
Particle Density ◽  
Quantum Fields ◽  
Local Conservation ◽  
Interaction Picture ◽  
Gauge Invariant ◽  
Spinor Fields ◽  
Quantum Particles ◽  
Natural Choice ◽  
The Green Function

A new approach to the concept of particles and their production in quantum field theory is developed. A local operator describing the current of particle density is constructed for scalar and spinor fields in arbitrary gravitational and electromagnetic backgrounds. This enables one to describe particles in a local, general-covariant and gauge-invariant way. However, the current depends on the choice of a 2-point function. There is a choice that leads to the local non-conservation of the current in a gravitational or an electromagnetic background, which describes local particle production consistent with the usual global description based on the Bogoliubov transformation. The most natural choice based on the Green function calculated using the Schwinger–DeWitt method leads to the local conservation of the current, provided that interactions with quantum fields are absent. Interactions with quantum fields lead to the local non-conservation of the current which describes local particle production consistent with the usual global description based on the interaction picture.

Quantum Fields

2020 ◽  
pp. 227-238
Author(s):  
Daniel Canarutto
Keyword(s):  
Field Theory ◽  
Gauge Field ◽  
Brst Symmetry ◽  
Gauge Field Theory ◽  
Quantum Fields ◽  
Spinor Fields ◽  
Lagrangian Field Theory

The basics of a Lagrangian field theory of quantum fields are laid down by exploiting the differential geometric notions introduced through F-smoothness. Infinitesimal vertical symmetries and currents in this setting lead, in particular, to the notion of BRST symmetry. The above results are applied to a fairly detailed study of a sample gauge field theory which includes spinor fields and ghosts.

Meaning

2017 ◽  
Author(s):  
Richard Healey
Keyword(s):  
Quantum Theory ◽  
Physical Object ◽  
Quantum Fields ◽  
Conceptual Content ◽  
Classical Physics ◽  
Physical Context

Novel quantum concepts acquire content not by representing new beables but through material-inferential relations between claims about them and other claims. Acceptance of quantum theory modifies other concepts in accordance with a pragmatist inferentialist account of how claims acquire content. Quantum theory itself introduces no new beables, but accepting it affects the content of claims about classical magnitudes and other beables unknown to classical physics: the content of a magnitude claim about a physical object is a function of its physical context in a way that eludes standard pragmatics but may be modeled by decoherence. Leggett’s proposed test of macro-realism illustrates this mutation of conceptual content. Quantum fields are not beables but assumables of a quantum theory we use to make claims about particles and non-quantum fields whose denotational content may also be certified by models of decoherence.

scholarly journals A path integral formulation for particle detectors: the Unruh-DeWitt model as a line defect

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Ivan M. Burbano ◽  
T. Rick Perche ◽  
Bruno de S. L. Torres
Keyword(s):  
Path Integral ◽  
Degrees Of Freedom ◽  
Wilson Line ◽  
Transition Probability ◽  
Relativistic Quantum ◽  
Quantum Fields ◽  
Line Defect ◽  
Particle Detectors ◽  
Nonlocal Operators ◽  
Detector Model

Abstract Particle detectors are an ubiquitous tool for probing quantum fields in the context of relativistic quantum information (RQI). We formulate the Unruh-DeWitt (UDW) particle detector model in terms of the path integral formalism. The formulation is able to recover the results of the model in general globally hyperbolic spacetimes and for arbitrary detector trajectories. Integrating out the detector’s degrees of freedom yields a line defect that allows one to express the transition probability in terms of Feynman diagrams. Inspired by the light-matter interaction, we propose a gauge invariant detector model whose associated line defect is related to the derivative of a Wilson line. This is another instance where nonlocal operators in gauge theories can be interpreted as physical probes for quantum fields.

Gårding Domains and Analytic Vectors for Quantum Fields

1972 ◽  
Vol 13 (6) ◽  
pp. 821-827 ◽  
Author(s):  
Gerhard C. Hegerfeldt
Keyword(s):  
Quantum Fields

scholarly journals Interacting quantum fields in various charts of anti–de Sitter spacetime

2021 ◽  
Vol 103 (4) ◽  
Author(s):  
E. T. Akhmedov ◽  
A. A. Artemev ◽  
I. V. Kochergin
Keyword(s):  
De Sitter Spacetime ◽  
Quantum Fields ◽  
De Sitter ◽  
Sitter Spacetime
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