Recent content by grilo

Just for completeness... I think it's OK to swap limits and integrals as long as you're using a Lebesgue integral. But I don't know much further, so... if someone could help on this... (:

Ah... thanks! I kinda thought that, but was afraid of being lousy. I try to keep my physics as mathematically rigorous as possible, so sometimes I run into those little issues. (: Thanks again!

Homework Statement (from "Advanced Quantum Mechanics", by Franz Schwabl) Show, by verifying the relation \[n(\bold{x})|\phi\rangle = \delta(\bold{x}-\bold{x'})|\phi\rangle\], that the state \[|\phi\rangle = \psi^\dagger(\bold{x'})|0\rangle\] (\[|0\rangle =\]vacuum state) describes a...

Is this idea of "approximate symmetry" and "pseudo-Goldstone bosons" rigorous? Better put: How rigorous are those ideas? Also, is there no chiral symmetry with massive quarks? (I'm kinda not used to the idea of a chiral symmetry)

Why in QCD chiral symmetry breaking study only the light quarks are taken into account? And why are their masses usually set to zero, Goldstone bosons are found, and then their masses are corrected by letting the quarks have non-zero mass? What happens if one study this symmetry breaking with...

Trying to solve the ODE mx''(t) + bx'(t) + kx(t) = F(t) with m measured in Kg, b in Kg/s and Kg/s^2, F(t) in Kgm/s^2 and x(t) in m with initial conditions x(0) = 0 and x'(0) = 0, i got the following Green's function G(t,t') = \frac{1}{m\omega} e^{-\omega_1(t-t')}\sinh\left[\omega(t-t')\right]...