Recent content by Sunset

Oh ok, thought you were talking about fields in cylindrical coordinates. Since you're talking about space-time in cylindrical coordinates, my atachement is of course of no use for you. Best regards

Quantum mechanics has the same form as 1+0 dimensional QFT. I found the propagator in cylindrical coordinates in a paper of Grosche http://www.iop.org/EJ/abstract/0305-4470/30/5/025" (see also the attachment) I think one should only add the \int d^3 x in the exponential. The problem is that...

Hi DrFaustus! Did you have a look in Kleinert's book on Path Integrals? He did a lot in curvelinear coordinates, maybe you find something. Best regards

:-) That's the point. You cannot track with your human eye how the electron moves. We humans only know a probability (the square of the electron wave function) where to find the electron in a position measurement. You cannot observe momentum and position simultaneously, so even superman could...

As far as I know there is no settled theory of Quantum Gravity so far. However, there are proposals. One of these proposals, as far as I understood Kaku, is a supersymmetric theory, so called "super-gravity". He states the Lagrangian in chapter 20, I attached it. Best regards

Hi luxiaolei! You're welcome. Maybe a word on that issue. Of course one cannot observe the particles by staring at them with one's eyes. Nobody saw an electron with his bare eye. In order to observe an electron one has to be more rude: one has to shoot other particles on it. From the...

Hi luxiaolei! Energy conservation can be indeed violated, but one cannot observe such processes experimentally. Processes which violate energy conservation (so-called "off-shell" processes) are "virtual". They appear in the internal structure of Feynman diagrams. Experimentally one can only...

Hi divB! You're absolutely right. There is a plus sign in the 3rd bracket and some confusion with factors of i in (3.140). I found a later version of his book, where the errors are corrected. I attached a bmp of the relevant page. Enjoy the book! Best regards Martin

I guess he refers to the fact that a quantum field theory of gravity would be non-renormalizeable. This can be easiliy seen from the dimension of the coupling. If one tries to quantize the classical field theory of gravity (General relativity), one faces the problem that the coupling constant (G...

Hi kazparov! In his book "Quantum Field theory - a modern introduction" there's a chapter on Quantum Gravity. If you don't know where to find the book, just send me a PM. best regards, Martin

Yes you were, thanks again!

Hi! I had a discussion with someone from the institute here, he told me mass M in the formula \xi=1/M relates only to the particle p_1 and not to the Goldstone mode p_2. I guess, this is what you said earlier. Ok, thanks for your help! Martin

Hi! I haven't been in office yesterday, too. So I wasn't able to reply until now. I googled a bit and found two papers related to the topic. The ginsparg-file (page 60) says that "when the correlation length diverges, the theroy becomes massless" The other one says (in chapter 4)...

>It is not true that the goldstone mass is \propto \xi^{-1} But in Field Theory sense, the inverse correlation length (dependent of temperature T) is the smallest mass appearing within the model. (Zinn Justin - Quantum Field Theory and Critical Phenomena, chapter 20.1). So, if a massless...

>Well, first of all, Z_2 breaking does not lead to goldstone bosons anyway, but never mind... I admit it's a bad example :redface:, Z_2 is not continous, so better consider O(2). At T=0 we have the potential V= (\vec{p})^2 + ((\vec{p})^2)^2 >Does that potential look symmetric to you...