EFT recipe

Last updated Aug 5, 2023

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Constructing an EFT: Recipe

1. Identify energy scales $\Lambda_H$ and $\Lambda_L$ and cutoff $\mu$
2. Identify degrees of freedom (d.o.f) for $<\mu$
3. Identify symmetries
4. Write down most general Lagrangian from the d.o.f. consistens with the symmetries (infinite terms)
5. Identify relative importance of terms by power counting.
6. Choose accuracy $(\frac{\Lambda_L}{\Lambda_H})^N$ to drop higher order terms.
7. Determin Wilson coefficients by matching amplitudes or Greens functions in full theory and EFT up to $(\frac{\Lambda_L}{\Lambda_H})^N$