Effective field theory Definition and 21 Threads

In physics, an effective field theory is a type of approximation, or effective theory, for an underlying physical theory, such as a quantum field theory or a statistical mechanics model. An effective field theory includes the appropriate degrees of freedom to describe physical phenomena occurring at a chosen length scale or energy scale, while ignoring substructure and degrees of freedom at shorter distances (or, equivalently, at higher energies). Intuitively, one averages over the behavior of the underlying theory at shorter length scales to derive what is hoped to be a simplified model at longer length scales. Effective field theories typically work best when there is a large separation between length scale of interest and the length scale of the underlying dynamics. Effective field theories have found use in particle physics, statistical mechanics, condensed matter physics, general relativity, and hydrodynamics. They simplify calculations, and allow treatment of dissipation and radiation effects.

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  1. P

    B Are real theories undiscoverable from effective field theories?

    In a podcast episode, Sean Carroll discusses Wilson's renormalization group and effective field theories, arguing how Wilson showed that upper-level theories are not discoverable from effective field theories at low energy. Excerpt: In what sense is this true? Does that mean that no matter how...
  2. S

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  3. E

    A Some basic questions about effective field theory (EFT)

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  4. E

    A The vertex factors in QCD penguin operators

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  5. E

    A Operator Product Expansion as shown in Schwartz

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  6. M

    I How to determine matching coefficient in Effective Field Theory?

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  7. A

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  8. I

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  9. T

    A Quantum Gravity: Renormalization vs. Effective Field Theory

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  10. S

    A Wilsonian RG and Effective Field Theories

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  11. Ken Gallock

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  12. B

    A Effective field theory in Srednicki's book

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  13. P

    A Understanding the Use of Trace in QFT Lagrangian for Chiral Symmetry in QCD

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  14. Luca_Mantani

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  15. M

    New properties of "standard model effective field theory"

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  16. atyy

    Effective field theory, black hole evaporation, firewalls

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  17. S

    What is an effective field theory?

    What is an effective field theory?? Yeah, there is many information on Internet, but it is a complicated level, they speak about cut-off, top-down, series development without justify limit the coefficients of ignored terms in the development. Aren´t there a simple (but rigurous) explanation...
  18. S

    What is an effective field theory?

    What is an effective field theory?? Yeah, there is many information on Internet, but it is a complicated level, they speak about cut-off, top-down, series development without justify limit the coefficients of ignored terms in the development. Aren´t there a simple (but rigurous) explanation...
  19. K

    Effective field theory and Wilson's renormalization group

    I have just read my first course on Quantum Field Theory (QFT) and have followed the book by Srednicki. I have peeked a bit in the books by Peskin & Schroeder and Ryder also but mostly Srednicki as this was the main course book. Now, I have to do a project in a topic not covered in the course...
  20. L

    Wilsonian effective field theory

    Hi, could anyone explain to me why in effective field theory (as in ch29 srednicki), you look at diagrams with only k<\Lambda as external lines and k>\Lambda for your interal lines? why do these diagrams with say, 6 external legs of this type, equate to the constant c_6 say? In previous...
  21. R

    What is an effective field theory

    Can anyone tell me if this is the basic concept behind effective field theories: 1) You begin with your original Lagrangian, and you want to construct an effective Lagrangian out of it. 2) You redefine your coupling constants in your original Lagrangian so that they include the integral...
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