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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 ...
Stephen Barr said about the book, "Like the famous Feynman Lectures on Physics, this book has the flavor of a good blackboard lecture". [3] Michael Peskin's review in Classical and Quantum Gravity said, "This is quantum field theory taught at the knee of an eccentric uncle; one who loves the grandeur of his subject, has a keen eye for a slick argument, and is eager to share his repertoire of ...
In mathematical physics, constructive quantum field theory is the field devoted to showing that quantum field theory can be defined in terms of precise mathematical structures. This demonstration requires new mathematics , in a sense analogous to classical real analysis , putting calculus on a mathematically rigorous foundation.
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, 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.
John Cardy in 1988 considered the possibility to generalise C-theorem to higher-dimensional quantum field theory.He conjectured [2] that in four spacetime dimensions, the quantity behaving monotonically under renormalization group flows, and thus playing the role analogous to the central charge c in two dimensions, is a certain anomaly coefficient which came to be denoted as a.
The study of such theories is conformal field theory. The coupling parameters of a quantum field theory can run even if the corresponding classical field theory is scale-invariant. In this case, the non-zero beta function tells us that the classical scale invariance is anomalous.