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It's well-known that there are no rigorously constructed and physically relevant QFTs. There is, however, a lot of mathematical work on effective field theories and renormalization, such as the books by Costello and by Salmhofer. My question is: does this mathematical work allow one to give mathematically rigorous (albeit effective, possibly depending upon empirical parameters) derivations of the physical computations one does with QFT (such as the electron magnetic dipole moment, say, or Compton scattering, this sort of thing)? If not, how far are we from being able to do so?

I ask because as somewhat of an outsider it seems hard for me to tell. Books that intend to give an account of these computations, like Folland's Quantum Field Theory, are very far from rigorous. The mathematical books on renormalization and effective field theories such as the ones I mentioned seem to be rigorous (although I have not read them in any amount of detail), but they also don't seem to discuss fundamental physics (or maybe I just missed it).

YCor
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Pedro
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    As far as I'm aware, Costello's approach is fundamentally perturbative: i.e. the planck constant is considered to be a formal parameter, and issues of convergence are not treated. So it can't be used to construct an "actual" QFT in the sense of the usual axiomatizations. – user1092847 Jun 24 '21 at 04:52
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    Have you considered searching this site for the keywords 'rigorous' and 'QFT'? – Igor Khavkine Jun 24 '21 at 09:37
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    you mention a problem like a calculation of the "electron magnetic dipole moment" --- this quantity is only known as a perturbation series in the fine structure constant; are you interested in a "rigorous" calculation of the coefficients in this expansion, or do you wish a nonperturbative calculation? The latter does not exist, rigorous or not. – Carlo Beenakker Jun 24 '21 at 11:39
  • @IgorKhavkine I have looked at several questions here but they all seem to be concerned with the construction of rigorous QFTs à la Wightman axioms etc., and not effective field theories. – Pedro Jun 24 '21 at 14:34
  • @CarloBeenakker The question is about the former, a mathematically well-defined but still perturbative version of these computations. Perhaps if convergence isn't known my question is to what extent can they be made well-defined rigorously. – Pedro Jun 24 '21 at 14:36
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I will leave aside what is meant by "effective field theory" in a purely mathematical context and just presume that the question asks whether renormalized interactive perturbative QFT (using formal power series in $\hbar$ and the coupling constants) can be mathematically well-defined. The answer is Yes (in multiple different ways), which has been repeated on this website several times (it is sufficient to search with the corresponding keywords). But it seems that there was not much interest in references before. So here are some references for what I consider to be a fairly clean approach of perturbative algebraic QFT. The list mixes older and newer references, as well as more and less readable references.

The work of Costello and Gwilliam is a different formalism, but could also be cited as an example. Perhaps others can add answers with references to their own favorite approach.

Igor Khavkine
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  • Thank you for the references. The Steinmann book is particularly relevant since it includes a discussion of Compton scattering in the last section. – Pedro Jun 24 '21 at 21:04
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    Since the question mentions examples from $QED_4$, I would also add to the list the book "QED: A proof of renormalizability" by Feldman, Hurd, Rosen and Wright. If one wants more precise results, I suppose one needs to incorporate more features of the Standard Model. But then, things might not be rigorous anymore. AFAIK there is no rigorous proof of perturbative renormalizability of the full Standard Model. – Abdelmalek Abdesselam Jul 14 '21 at 16:57