Recent content by marcom

Perhaps because: ##\int_{-\infty}^{0} f(x)dx##=##-\int_{0}^{-\infty} f(x)dx##=##-\int_{0}^{+\infty} f(-x)d(-x)## ?

Sorry to talk again about this but normally exchanging the limits of integration only introduces a minus sign ∫ ab=-∫ba And the result wouldn't be the same, so I don't understand why the substitution p -p works. (And to be precise in the book they calculate the integral from infinity to I am...

OK, thanks a lot for your help!

I obtain: ∫d|p||p| e-it (√|p| 2 + m 2)(ei|p||x|+e-i|p||x|)

Thanks but I didn't understand

Hi, Could you please help me understand the following example from page 76 of "QFT for the gifted amatur"? I can't see how the following integral becomes Thanks a lot

Hi, Could you please explain me why, under the transformation of a complex valued field Φ→eiαΦ, for an infinitesimal transformation we have the following relation? δΦ=iαΦ Thanks a lot

Hi, I'd like to ask you if you could write a list of QFT books in order of increasing difficulty. Thanks!

Thanks!

Hi, I've never studied compex analysis before but I am trying to understand this example from "QFT for the gifted amatur". I don't understand why the residue at the pole is e-iEp(t-t')e-e(t-t'). How did the find e-e(t-t')? Thanks.

https://fliptomato.wordpress.com/2006/12/30/from-griffiths-to-peskin-a-lit-review-for-beginners/

OK, it's an eigenfunction of p2, isn't it? ψn=(√2/a) sin (nπx/a) (d2/dx2) sin (nπx/a) = -(nπ/a)2 sin (nπx/a) p2ψn=-(iħ)2 (nπ/a)2ψn=(nπħ/a)2ψn

I found a page in the same site that proves my point: "the momentum is equally likely to be in either direction. The magnitude of the momentum is a constant, since this is a state with fixed energy, and " http://physicspages.com/2012/09/13/infinite-square-well-momentum/

I think that my question is wrong, the momentum is quantized actually. En=n2π2ħ2/2mL2 Pn2=2mEn=2mn2π2ħ2/2mL2 Pn=±nπħ/L

Hi, I have a problem understanding the particle in a box (V=0 inside, V=∞ outside), how is it possible that momentum can vary continuously while the energy spectrum is discrete? Aren't they related by E=p2/2m? What I am missing? Thanks!