Recent content by peguerosdc

Hi! Instead of just describing my procedure and all my derivations, I really just want to ask if my approach makes sense (actually I have 2 options) to calculate the maximum energy. I am considering c=1 and the problem suggests to consider the neutrino massless: For the first decay, ##Z...

Yeah, I almost missed that and actually I think that's the convention followed in every book, so it's worth noting it for future readers that check this thread. Thank you for showing the full derivation! Definitely helpful.

Oh, right! I knew this was most likely a dumb question. Thanks!

Thanks for the reply! Yes, I think that's why 37.28 implies 37.29, but my question is more how to get to equation 37.28. Following Srednicki, if you just plug 37.27 into 37.23, you get: $$ \begin{align*} (-\not\!p + m) ( u(\mathbf p) e^{ipx} + v(\mathbf p) e^{-ipx} ) &= 0 \\ (-\not\!p +...

Hi! I am studying Dirac's equation and I already have understood the derivation. Following Griffiths, from factoring Einstein's energy relation with the gamma matrices: ## (\gamma^\mu p_\mu + m)(\gamma^\mu p_\mu - m) = 0 ## You take any of the two factors, apply quantization and you arrive to...

Thanks everyone for the replies! Then, what would be the physical scenario here? I mean, I suspect the wave function must collapse because when we measure/determine position of let's say an electron, we find a well defined position in space. So, in the momentum representation, does this mean...

Thanks for the reply! I am not sure if I understand this as a subtlety or if there is a deeper meaning. We could say that "measuring" is a way of "determining" the value of an observable. When you perform a measurement, the wave function collapses and the value of that observable is well...

Hi! I am checking Zettili's explanation on the uncertainty principle and I have this confusion on what the "uncertainty" really means which arises from the following statements: When introducing the uncertainty principle, for the case of position and momentum it states that: if the x-component...

Got it! Your example helped me a lot. Thank you!

@mfb thanks for your reply! From what I read in Griffiths', due to energy conservation if ##m_a > m_b##, (where ##m## stands for mass) then I would need to supply enough energy to make it up in the reaction ##b \rightarrow a##. Is this what you mean? And, starting from a given reaction...

Hi! This is a very very noob question, but I am starting to get into particle physics and I don't understand the application of crossing symmetry in the inverse beta decay. Crossing symmetry says (from Griffiths) that, in a reaction "any of these particles can be 'crossed' over to the other...

So, I did some research on this and I found equation (**) slightly different on the textbooks as they state that the transformation is canonical if: ##M^T J M = J## Where ##T## stands for "transpose". If this is the case, this would lead to the following relations for the Poisson brackets for...

That we can't find a function ##f## such that ##f = f(q)## that makes my system satisfy Hamilton's canonical equations because we reached a contradiction defining ##f = f(q)## and then finding that we needed ##f = f(q,p)##. So, if this is correct, then there is no ##H## for these equations of...

So, ##\dot p = - \frac {\partial f} {\partial q}## but we also know that ##\dot p = - q - \gamma p##. Then, by comparison ##\frac {\partial f} {\partial q} = q + \gamma p## but we stated that ##f=f(q)##, so we will not be able to find a suitable ##f## as we would need ##f=f(q,p)##. If this...

Thanks for your reply! So, after plugging H into the second equation, I got: ## \dot p = - \frac {\partial f} {\partial q} ## But before proceeding with my interpretation of this, I would like to improve my understanding of the theory as that's the main reason I am not sure how to approach...