Recent content by Dox

Thank you fzero. I've found out that people use to write a commutator for this factor but it is just a wedge product... that's why I was getting a different factor of 2. THX.

Hi everyone, Homework Statement I've been studying a paper in which there is a connection given by, A = f(r)\sigma_1 dx+g(r)\sigma_2 dy, where \sigma's are half the Pauli matrices. I need to calculate the field strength, F = dA +[A,A]. Homework Equations A = f(r)\sigma_1...

Hi everyone, I've been studying a paper in which there is a connection given by, A = f(r)\sigma_1 dx+g(r)\sigma_2 dy, where \sigma's are half the Pauli matrices. I need to calculate the field strength, F = dA +[A,A]. I have computed it, but a factor is given me problems. I would say, dA =...

Ha ha ha... Impressively accurate!

Those are the branes... Isn't it? Look at the Lagrangian of Dp-branes, those are just the generalization of the Nambu-Goto action of the strings.

That's it! Moreover, spin is as important as the angular momentum... because it's like an extra-contribution to the classical angular momentum. Regards.

I'd say an intrinsic charcteristic of particles... such as a mass. So, why is it important?

Hi everybody! I'm studing some classical field theory in general backgrounds. Of course the most beautiful way of doing so is using differential forms. For example, the lagrangian density of a massless scalar field would be L_{\phi}=d\phi\wedge * d\phi, while the lagrangian density for a YM...

In this cases I prefer the Quantum Mechanics notation, so from Ad(Y)\left. |X\right>=\left. |[Y,X]\right>, It is trivially to find the ``matrix element'' \left<Z|Ad(Y)|X\right>= \left<Z|[Y,X]\right>. So, since the commutators of the basis elements are known, the problem is solved...

I mean: The condition is r(0)=r(1). In general a function satisfying that condition could be expand as a Fourier series, Isn't it? Because sine and cosine are periodic functions.

Thanks for your answer Quasar987, but that exactly the point. In order to satisfy the boundary condition I must expand in Fourier series, Isn't it? Thank you very much.

Hello. In a certain problem I'm interested on, I need to write a general form of the parametrization of a closed curve on \mathbb{R}^3. I thought in parametrize it using a kind of Fourier series. Could it be possible? Thing become even worse 'cause I'd like to the curve doesn't cross...

From time to time one met a genius... one of that guys are incredible. Around three years ago I was at ICTP and one of my classmates(and a good friend of mine) got a perfect 4. (that was not my case... at all). Of course we agree it depends on where you're studing... Ok, but Witten exists...

Hello. I don't understand what is your question... perhaps you can rearrange it a little bit. So... This is an statement. Is this your answer or part of your problem? This seems to be a guess of yours, Isn't it? If you put it clearer, so we can help :wink: Regards.

Hello. I think that using Lagrange's methods won't help you. The best you can do is using Newton... use vectors! Regards.