Schwinger's Quantum Action Principle. I. From Dirac's Formulation through Feynman's Path Integrals to the Schwinger-Keldysh Method

K. A. Milton

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arXiv · 1402.3762

Schwinger's Quantum Action Principle. I. From Dirac's Formulation through Feynman's Path Integrals to the Schwinger-Keldysh Method

K. A. Milton

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Abstract

Starting from the earlier notions of stationary action principles, we show how Schwinger's Quantum Action Principle descended from Dirac's formulation, which independently led Feynman to his path-integral formulation of quantum mechanics. The connection between the two is brought out, and applications are discussed. The Keldysh-Schwinger time-cycle method of extracting matrix elements is described. Part II will discuss the variational formulation of quantum electrodynamics and the development of source theory.

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K. A. Milton. 2014-02-16. Schwinger's Quantum Action Principle. I. From Dirac's Formulation through Feynman's Path Integrals to the Schwinger-Keldysh Method. https://arxiv.org/abs/1402.3762

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