Recent content by rubbergnome

That will be a great reference for my paper :) you're welcome! Even though I made a typo (d3 is supposed to be k3) and it seems I can't edit my post.

Hi :) let's see about the questions: 1. The integral reduces to that because it's in 4 dimensions, so that d4k = k3dk dΩ changing to (hyper-)spherical coordinates. This cancels the k2 in the denominator leaving k, and you can trivially do the angular integral of course. 2. If you swap the...

Thanks for responding. I actually used a modified Zeta Regularization technique. First of all I imposed that space must be a d-dimensional subspace of \mathbb{R}^n. Then I defined the \delta distribution via the usual "Fourier transform of 1", but integrating in d dimensions, even though the...

Hi guys. I'm working on a model described by a non-local QFT. I think I got the Feynman rules right, but I get divergences from ##\delta(0)##-like factors.Homework Statement It's a QFT for a complex scalar field ##\psi(x)=\psi(\mathbf{x},t)## with action $$S= \int dx...

For some reason I cannot edit the first post anymore. I just wanted to add that x-linearity in f is not required, also because if compromises the positivity. I needed it for other things, but I realized it's not working that way. Deriving the equations of motion shouldn't depend on that anyway.

I need to derive the euler-lagrange equations for the following non-local lagrangian density for a complex scalar field ψ \mathcal{L} = \partial_{\mu}\psi^* \partial_{\mu}\psi - \lambda \int dy\, f(x,y) \psi^*(y) \psi(y) where λ is the coupling constant, f is a certain real-positive valued...

Thanks a lot. I have many doubts about this, especially since I read papers in which the main objects of the theory where nets of Von Neumann algebras, and there was no reference at things like scattering amplitudes or path integrals to study processes, only observables. I mean, maybe one can...

"Smeared" quantum fields in everyday QFT Hello everyone. I have a question regarding algebraic QFT. I read that, in order to avoid ill-defined, divergent expressions like the mode expansions for spacetime-dependent field operators φ(x), one starts from the (Wightman?) axioms, using...

Why not? I mean, the Schrodinger equation expresses nothing more than the fact that the Hamiltonian is the infinitesimal generator of time translations. In Dyson's formula, one uses the time integral of the Hamiltonian density from initial to final time, rather than Ht where H is...

I think this is just an analogy taken from QM to QFT. I assume ∅ here is an operator. This is just the definition of the Heisenberg picture, which one derives from the way the time evolution operator acts. And the way the time evolution operator acts is pretty much the Schrodinger equation...

After realizing that your links contain everything, my 'other questions' was really just referring to the first one. Now you answered that as well :) sorry to have bothered you.

Oh yeah, I didn't keep track of that. Thanks. I hope someone will answer the other questions :) Also, the posts in the second link about representations are really clear, thanks a lot!

I know, it's just that it's been a couple of years that I read books and followed video lectures, all the way from calculus to this stuff, and although It's kind of a basic understanding, I can tell you I was able to grasp the maths in this course...

Hello everyone, I'm an high school student, but I try to study maths and physics at a decent level anyways. I have some questions to pose; to give you an idea of how could you guys answer me, i recently finished viewing David Tong's QED video lectures and notes, and I'm stuck at the CFT sections...