Recent content by Xela

Actually, I don't. The classical calculation is done simply by calculating the trajectory of a point charge in a Coulomb potential - e.g. Rutherford scattering: http://en.wikipedia.org/wiki/Rutherford_scattering or in more detail here...

Do you mean that this can be probably fixed by higher-order IR divergent terms? Similar to the solution of Bremsstrahlung IR divergence? I couldn't find anything like that in the literature

I appreciate your efforts to help very much, and it is not a matter of me "bothering writing down the formula". I'm just new here, and I have no idea how to display equations in posts. Here's a page in Mandl nad Shaw where the matrix element (Eq. 8.48a) diverges for p1=p1'...

Then why do QFT people worry so much about eliminating infrared and ultra-violate divergences in the theory? As much as going to string theory. If the theory has to be consistent only as far as experiment is concerned, and if no one can measure infinitesimal and/or infinite momenta - why bother?

I guess I'm not sure about one thing: Doesn't a theory have to be free of divergences regardless of the experiment. Is it a valid theoretical argument to say something like "this will take for ever to record" or "this requires infinite precision of equipment" so we don't have to worry about the...

Hi, As I see it - uncertainty is a fundamental concept, simply caused by the fact that in QM we're dealing with waves with all their inherent properties including diffraction. And with waves you can go only as small as their wavelength. So for your specific example, sending a low energy...

Thanks for the response. I also assumed that the divergence is false, but I want to understand why it is false. To be more specific: In QED, electron-electron scattering matrix there is a photon propagator with 1/(k1-k2), where k1 is the initial electron momentum and k2 is the final electron...

If I'm not wrong being a fermion/boson is irrelevant to having an antiparticle. What I remember is that the field has to be a complex one to have charge and antiparticles. Photon field is a real one. Charge conservation for for complex fields comes out of the invariance of the complex field...

Hi again. Well, I'm a bit surprised I didn't get any answers. If the subject doesn't look that interesting - I think it is interesting. Infinite probability without explanations of the simplest electron-electron scattering looks like a serious problem in QED, which is the most accurate...

Hi again. Well, I'm a bit surprised I didn't get any answers. If the subject doesn't look that interesting - I think it is interesting. Infinite probability without explanations of the simplest electron-electron scattering looks like a serious problem in QED, which is the most accurate...

I think yes - a very weak scattering. Or even if we decide to call this case "no scattering" - the calculation for this case is still problematic. I wouldn't be surprised if forward scattering probability would come out close to 1, but an infinite one looks like a mathematical problem Bhabha...

Thanks for the response. I guess I should formulate the question better. By "divergence" I mean an infinite result. This seems unphysical for probability amplitudes. The phenomenon here is: one electron is scattered by another one. In the matrix element for electron-electron scattering there...

Hi, I have a question about the divergence of forward Coulomb (Bhabha/Moller) scattering. I guess the classical analog of it is the Rutherford cross-section divergence, but that can be explained by the infinite impact parameter. In the QED version - the Bhabha/Moller scattering, it is...

Hi, I have a question about the divergence of forward Bhabha/Moller scattering. I guess the classical analog of it is the Rutherford cross-section divergence, but that can be explained by the infinite impact parameter. In the QED version - the Bhabha/Moller scattering, it is the matrix...

Hi. I have 2 questions about second-order coherence – g2(t): 1) For collision-broadened light according to the literature g2(t)=1+|g1(t)|^2, where g1(t) is the 1st order coherence. Therefore for very low collision rate g1(t) =1 and thus g2(t)=2. However I would expect collision broadened...