Recent content by Rocky Raccoon

Can someone refer me to Feynman rules for electroweak interactions in the general case of SU(2) multiplets of weak isospin n and weak hypercharge Y interacting with EW gauge bosons? I can only find the standard rules for SU(2) doublet electron - neutrino. Thanks!

You didn't lead me astray, I was thinking the same thing as you and it got me nowhere so I tried PF :)

Thanks for the response. I just found out that it can in fact be done (p. 93): http://www-com.physik.hu-berlin.de/~fjeger/ll.pdf

In the Kallen-Lehmann spectral representation (http://en.wikipedia.org/wiki/K%C3%A4ll%C3%A9n%E2%80%93Lehmann_spectral_representation) the interacting propagator is given as a weighted sum over free propagators. The pole of the integracting propagator is, of course, given by p^2=m^2, m being the...

Yes, you're absolutely right, I'm missing a factor of 2. So, you're saying that a simple change in variables will do the trick. I'll certainly try to do it that way. But, I was more thinking along the lines of solving the equation: dx^{\mu}=dc_{\nu}(2x^{\mu} x^{\nu} - g^{\mu \nu} x^2)? Can it...

While it's pretty easy to derive the infinitesimal version of the special conformal transformation of the coordinates: x'^{\mu}=x^{\mu}+c_{\nu}(x^{\mu} x^{\nu}-g^{\mu \nu} x^2) with c infinitesimal, how does one integrate it to obtain the finite version transformation...

So, in layman's terms - what's the difference between constants of motion and first integrals?

I am aware of that. But what if I have a Lagrangian and no clue as to which invariance conditions to check? Is there any way of making the Lagrangian tell me that it's invariant wrt (and only wrt) conformal transformations?

I thought there may be some equation with solutions that would give possible transformations that leave the action integral invariant?

Is there a systematically way of finding all space-time symmetries of a given Lagrangian? E.g. given a electromagnetic Lagrangian, can I somehow derive that the symmetries in question are conformal ones? Thanks.

Is there a classical analogy of Poisson brackets which anticommute?

This was never taught at my relativistic quantum mechanics class :( Even Greiner (a classic textbook) doesn't mention it. So, what is the basis for such an assumption?

How can I have anticommuting variables before I define my canonical momentum which defines canonical commutation relations?

OK, I thought so. But, with this Lagrangian, I get an extra factor 2 in my anticommutation relations compared to the standard anticomm. relations.

As is well known, a Dirac Lagrangian can be written in a symmetric form: L = i/2 (\bar\psi \gamma \partial (\psi) - \partial (\bar\psi) \gamma \psi ) - m \bar\psi \psi Let \psi and \psi^\dagger be independent fields. The corresponding canonical momenta are p = i/2 \psi^\dagger...