Definitions for effective action
ef·fec·tive ac·tion

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1. Effective action

   In quantum field theory, the quantum effective action is a modified expression for the classical action taking into account quantum corrections while ensuring that the principle of least action applies, meaning that extremizing the effective action yields the equations of motion for the vacuum expectation values of the quantum fields. The effective action also acts as a generating functional for one-particle irreducible correlation functions. The potential component of the effective action is called the effective potential, with the expectation value of the true vacuum being the minimum of this potential rather than the classical potential, making it important for studying spontaneous symmetry breaking. It was first defined perturbatively by Jeffrey Goldstone and Steven Weinberg in 1962, while the non-perturbative definition was introduced by Bryce DeWitt in 1963 and independently by Giovanni Jona-Lasinio in 1964.The article describes the effective action for a single scalar field, however, similar results exist for multiple scalar or fermionic fields.

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1. Effective action

   In quantum field theory, the effective action is a modified expression for the action, which takes into account quantum-mechanical corrections, in the following sense: In classical mechanics, the equations of motion can be derived from the action by the principle of stationary action. This is not the case in quantum mechanics, where the amplitudes of all possible motions are added up in a path integral. However, if the action is replaced by the effective action, the equations of motion for the vacuum expectation values of the fields can be derived from the requirement that the effective action be stationary. For example, a field with a potential, at a low temperature, will not settle in a local minimum of, but in a local minimum of the effective potential which can be read off from the effective action. Furthermore, the effective action can be used instead of the action in the calculation of correlation functions, and then only tree diagrams should be taken into account.

How to pronounce effective action?

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How to say effective action in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of effective action in Chaldean Numerology is: 3

2. Pythagorean Numerology

   The numerical value of effective action in Pythagorean Numerology is: 8

Examples of effective action in a Sentence

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2. Aizaz Ahmed Chaudhry:

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3. Brett Loper:

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References

1. ^ Wikipedia
   https://en.wikipedia.org/wiki/Effective_Action
2. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=effective action