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In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. [1]: xi QFT is used in particle physics to construct physical models of subatomic particles and in condensed matter physics to construct models of quasiparticles.
Quantum field theory originated in the 1920s from the problem of creating a quantum mechanical theory of the electromagnetic field.In particular, de Broglie in 1924 introduced the idea of a wave description of elementary systems in the following way: "we proceed in this work from the assumption of the existence of a certain periodic phenomenon of a yet to be determined character, which is to ...
This is a list of quantum field theories. The first few sections are organized according to their matter content, that is, the types of fields appearing in the theory. This is just one of many ways to organize quantum field theories, but reflects the way the subject is taught pedagogically.
In quantum field theory, correlation functions, often referred to as correlators or Green's functions, are vacuum expectation values of time-ordered products of field operators. They are a key object of study in quantum field theory where they can be used to calculate various observables such as S-matrix elements.
Algebraic quantum field theory (AQFT) is an application to local quantum physics of C*-algebra theory. Also referred to as the Haag–Kastler axiomatic framework for quantum field theory , because it was introduced by Rudolf Haag and Daniel Kastler ( 1964 ).
In quantum field theory n-dimensional integrals of the form (()) appear often. Here ℏ {\displaystyle \hbar } is the reduced Planck constant and f is a function with a positive minimum at q = q 0 {\displaystyle q=q_{0}} .
The theory of quantum field theory in curved spacetime may be considered as an intermediate step towards quantum gravity. [18] QFT in curved spacetime is expected to be a viable approximation to the theory of quantum gravity when spacetime curvature is not significant on the Planck scale.
In quantum field theory, partition functions are generating functionals for correlation functions, making them key objects of study in the path integral formalism.They are the imaginary time versions of statistical mechanics partition functions, giving rise to a close connection between these two areas of physics.