Recent content by bagherihan

What's the way to convert n(r) to \rho(r) in case of a spherical cloud. n(r) is the column density, \rho(r) is the density. I tried (but didn't manage) to get it from their relation to the total mass: M = 4 \pi \int r^2 \rho(r)dr = 2 \pi \int r n(r)dr (is it correct anyway?) Thank you,

You're probably right, it's the 6 dof of B that matters. But apparently B has a gauge symmetry, so only 3 dof left.

Thanks ChrisVer, A^\mu has nothing to do with B_{\mu \nu} I meant the number dof of the theory. H_{\nu ρσ} is antisymmetric, so it has only \binom{4}{3}=4 dof, doesn't it? thus in total it's 3X4=12 dof, isn't it? And more important for me is to know the action symmetries, both the global and...

S=\int d^4x\frac{m}{12}A_μ ε^{μ \nu ρσ} H_{\nu ρσ} + \frac{1}{8} m^2A^μA_μ Where H_{\nu ρσ} = \partial_\nu B_{ρσ} + \partial_ρ B_{σ\nu} + \partial_σ B_{\nu ρ} And B^{μ \nu} is an antisymmetric tensor. What are the global symmetries and what are the local symmetries? p.s how...

I mean for example that I saw that for the scalar field it is : j^{μσμ} = x^ρT^{\mu \sigma} - x^σT^{\mu ρ} I don't know how to get there, so I'd like to see the full derivation.

Is there anywhere I can see the explicit derivation for a massless real scalar and for the EM field? thank you.

E = - grad*phi - 1/c (dA/dt). phi is the scalar potential, and is given. How do I calculate the vector potential = A ? Is it A = (v/c) * phi ? If it is, then where is this equation coming from? Thank you.