it is boring, if……

Update: This is manifestly wrong.

The algorithm of constructing EFT is simple, as follow. (Remark that this algorithm holds not only for fields, but also for any other physical object which has a spectrum.)

1. Propose the fields and their types (such as tensor, or spinor) that the theory involves; and symmetries that the theory must keep. This can be guessed via physical situation.

2. Write down the most general action constructed by those fields, satisfying all symmetry restrictions in 1, with a UV and IR cut-off of the spectra of fields. Usually, this action has infinitely many terms; but not always so.

3. Perform re-scaling of spectrum, so that the energy-scale of the physical process cared about, usually characterized by the cut-offs of spectra, is absorbed into other quantities in action, removed from spectra, and involved into the coefficients in the action.

4. The dependence of re-scaled coefficients on energy-scale can effect which terms dominate the theory and which are negligible under a given energy-scale of physical process. (For different energy-scale, it maybe different terms that dominate.)

5. First make an educated guess, that is, pick several largest coefficients, whose terms are proposed to have the dominate role in the theory, while neglect the others; then do calculation with this reduced action; and then comparing your results with experiments, fixing the parameters (now you have the least number of parameters).

6. If it fits, that OK. If not, then involve the term that is guessed as sub-dominate into your calculation, still neglecting the left that were neglected. Then re-do all the procedure, to see if your theory fits the experiments.

7. Re-do step 6 again and again, until it does fit, or until your theory contains so many parameters so that it is “non-trust-able”.

So, this is the “truth” we are seeking for. If so, it’s boring.