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We believe that the standard model is only an effective field theory of its true UV completion. However, effective theories have dimensionful couplings and are not renormalizable. The standard model has dimensionless couplings and is renormalizable. So then how is the standard model both an effective theory but also renormalizable?

Edit: Is this the answer: if we have a theory with dimensionless couplings, then look at it on a lower energy scale, it will look like an effective theory with dimensionful couplings. But a "grand unified theory" won't have dimensionless couplings. It will have dimensionful couplings, perhaps with the size of the planck mass. So while the standard model might be an "effective theory" of the "grand unified theory," it has dimensionless couplings instead of dimensionful couplings, because the "grand unified theory" already had dimensionless couplings that are irrelevant at our scale.

Is that a correct answer?

Edit 2: My question is different from other "why is the standard model renormalizable" questions because I am asking why the standard model is renormalizable given that it probably is an effective field theory.

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    $\begingroup$ "However, effective theories have dimensionful couplings and are not renormalizable." - This is a statement about an effective QFT that comes from an UV complete QFT. But do you really hear the claim that the Standard Model comes from a UV complete QFT? $\endgroup$ – ACuriousMind Dec 11 '18 at 20:11
  • $\begingroup$ Wouldn't a supersymmetric theory be a UV completion of the standard model? $\endgroup$ – user1379857 Dec 11 '18 at 20:17
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    $\begingroup$ "effective theories have dimensionful couplings and are not renormalizable" This is false. They may have them, but they need not. An effective theory at a free fixed point, for example, is purely gaussian (by definition). $\endgroup$ – AccidentalFourierTransform Dec 11 '18 at 20:27
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    $\begingroup$ Possible duplicate of Why should the Standard Model be renormalizable? $\endgroup$ – Thorondor Dec 11 '18 at 20:57