l33tman 3 days ago

It's a single lagrangian with a couple of dozen constants, in their pics there as well. It's just expanded out to different degrees.

  • baxtr 3 days ago

    Through smart definitions I can contract any longer term as much as I want.

    • Vampiero a day ago

      Yes and that's precisely why you're writing high-level code instead of ASM. It's your job.

    • l33tman 3 days ago

      Yes, and it's exactly those "smart definitions" that are the Standard Model. The whole goal is to produce even smarter definitions, including showing that as much as possible of it couldn't be any other way, preferably.

ajkjk 3 days ago

Nah it really is simpler than that, that picture has exploded the summations to make it look complicated. Although it is strangely hard to find the compressed version written down anywhere...

the thing about Lagrangians is that they compose systems by adding terms together: L_AB = L_A + L_B if A and B don't interact. Each field acts like an independent system, plus some interaction terms if the fields interact. So most of the time, e.g. on Wikipedia[0], people write down the terms in little groups. But still, note on the Wikipedia page that there are not that many terms in the Lagrangian section, due to the internal summations.

[0]: https://en.wikipedia.org/wiki/Mathematical_formulation_of_th...