Recent content by Kurret

Actually the paper I referred to just applies the Kubo formula in an AdS/CFT context, but they don't derive it (it just happened to be the place where I saw it). I am interested in a derivation of this formula indeed using standard linear response theory (nothing to do with AdS/CFT). Thanks for...

I am looking for a derivation of the following formula $$ \eta=\lim_{\omega\rightarrow0} \frac{1}{2\omega}\int dt dx\langle[T_{xy}(t,x),T_{xy}(0,0)]\rangle, $$ where $T_{xy}$ is a component of the stress-energy tensor. This is claimed in for instance https://arxiv.org/pdf/hep-th/0405231.pdf...

If you send a light ray straight through a star then of course (by rotational symmetry) it can not bend in any direction. The wavelength of the light will of course be affected by the gravitational field but the direction will not.

Yea...so that is sort of part of the problem. I guess it is not very likely that there are these positions after all, but that is also part of my question if it is possible at all. Edit: But I do know that there are people that have for example successfully conducted research in both string...

I am currently doing a PhD in theoretical physics (let's for simplicity say gravity and black holes). However, I have also in my free time been working a bit in a more applied field (let's say cold atom physics), and have been reasonably successful (in the sense that I have some publications...

Thanks for your replies. If you know any specific reading material, don't hesitate to post them :).

Thanks!

[Moderator's Note: Changed level of thread to "Advanced" based on the topics being asked about, all are graduate level topics.] I feel that I have an inadequate understanding of many important concepts in condensed matter physics, so I want to try to learn at least the most basic parts. So what...

I heard that this potential is exactly solvable (ie one can find the eigenstates of the quantum mechanical problem exactly). However, I can not find a reference. I heard it is in Merzbacher, but I can not find it. Is it correct that this is exactly solvable? Can someone provide a good reference?

I am trying to use the Israel junction conditions for a null surface, but I am running into complications with defining a normal vector for a null surface. As I understand it the normal vector is defined to be perpendicular to the surfaces tangent vectors n\cdot e_i=0, as well as satisfying...

In quantum mechanics, we can define the scattering amplitude f_k(\theta) for two particles as the coefficients of an outgoing spherical wave. More precisely, the asymptotic behaviour (when r\rightarrow\infty) of a wave function of two scattering particles, interacting with some short range...

As I understand it, the symplectic Lie group Sp(2n,R) of 2n×2n symplectic matrices is generated by the matrices in http://en.wikipedia.org/wiki/Symplectic_group#Infinitesimal_generators . Does this mean that sl(n,R) is a subalgebra of the corresponding lie algebra, since in that formula we can...

The additional sum is the only difference. Just substitute the equation just before to get rid of the inner three dimensional integral. I am not making this up, I have seen this divergent integral popping up several times without any comments about the obvious fact that it is wrong...

I agree with everything you are saying, but this is a formula I see quite often but I never understand what it means due to these issues. Just to throw in an example, look at page 5 before equation 1.11 of the following paper http://arxiv.org/pdf/0804.1773v1.pdf

If I understand your question right, you are looking for a reference about super manifolds, and not necessarily about supersymmetry in quantum field theory, which is what people usually mean when they say supersymmetry? If so, you can try to have a look at http://arxiv.org/abs/1209.2199 if you...