I asked the question Criterion for a Feynman loop diagram to give a finite value long back. Though it wasn't poorly received, I did not get an answer yet. What can I do to improve the question? Of course, I can offer a bounty but many times it has happened that I didn't get any answer even then.

  • 2
    $\begingroup$ Related: meta.physics.stackexchange.com/q/6586/2451 and links therein. $\endgroup$
    – Qmechanic Mod
    Commented Jul 1, 2018 at 16:58
  • $\begingroup$ Did AFT's comment in the post help provide a direction for you to self-answer? Or was it completely useless? (And if the latter, why not reply to him with why it didn't help any?) $\endgroup$
    – Kyle Kanos
    Commented Jul 2, 2018 at 18:19
  • $\begingroup$ @KyleKanos After AFT's comment, I'm waiting for ".. if someone could summarise the essential points here...". $\endgroup$
    – SRS
    Commented Jul 2, 2018 at 18:30
  • $\begingroup$ @SRS so rather than try researching it based on his directions (and possibly answering the question yourself), you're just waiting? $\endgroup$
    – Kyle Kanos
    Commented Jul 2, 2018 at 23:42
  • $\begingroup$ From my personal experience, sometimes you just gotta offer a second bounty, preferably significantly larger. $\endgroup$
    – knzhou
    Commented Jul 11, 2018 at 13:11

1 Answer 1


What can I do to improve the question?

No offence, but make it more interesting and a possible learning resource.

By that I mean, explain far more about what your problem is, how you arrived at that point and what you think possible solutions (that you are currently dismissing, based on your own assumption) are. Obviously there's a balance, you can can assume your audience knows what's involved in easier scattering problems.

It's a numbers game.

By writing the original question the way you have, as:

The contribution of loop diagrams in QFT are often divergent and sometimes convergent as well. For example, the self-energy corrections in QED are divergent. On the other hand, the Zee model of radiative neutrino mass (for example) induces a finite neutrino mass at one-loop.

you will only attract the relativity few heavy hitters on the site. And this hasn't worked.

By explaining in more detail what your problem is, you possibly will get the attention of students (a far larger proportion of site user and "outsiders" who are nearly at your level and are prepared to investigate something that they will need to cover eventually anyway).

The more you have to explain it, the better a question it is, in most cases, and the act of explaining it may make the penny drop for you.

Sure, you have been looking at this problem long enough yourself that you can sum it up succinctly to the cognoscenti, but there's very few (to date, none) of those here willing to answer.

So if I was asking the question, I would expand it as I said above. Loop diagrams are not (no offence again) the most difficult area of QFT. I don't know the answer, but I'm six months away from calculating those amplitudes and I guess many others are as well.

Maybe (probably) you won't get an answer from less experienced users, but they might give you an idea of how it could be resolved, or a link to a paper or tutorial or presentation where it has been covered.


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