Timeline for Guidance needed in finding scattering amplitude
Current License: CC BY-SA 3.0
23 events
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| Nov 3, 2014 at 22:42 | comment | added | Fluctuations | Thank you Prahar. Sorry, I do apologize for all the mess I made around here. The thing is I am really confused about this and how to proceed that I didn't even understand the problem. @Prahar does this process have a name so I can read about it to know how to proceed with this. Or what are the specific Feynmann rules for this theory.. Your help and time are much appreciated! | |
| Nov 3, 2014 at 22:29 | history | edited | Prahar | CC BY-SA 3.0 |
clarified the exact scattering process that the OP is interested in computing (based on comments)
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| Nov 3, 2014 at 22:28 | comment | added | Prahar | @Fluctuations - See the thing is, for the same Lagrangian, I could have computed the scattering amplitude for $\phi \phi \to \phi \phi$ or $\psi \psi \to \psi \psi$ each of which would have different answers even though the theory is the same. Thus, to even discuss a scattering amplitude, you need to give the theory and the exact process that you are interested in. | |
| Nov 3, 2014 at 22:26 | comment | added | Prahar | @Fluctuations - So the process you are interested in is $\psi \phi \to \psi \phi$. That is an important piece of information. You should clearly mention this in the problem. | |
| Nov 3, 2014 at 22:03 | comment | added | Zo the Relativist | Your professor probably just wanted there to be an implied $\frac{1}{2}\partial_{\mu}\phi\partial^{\mu}\phi$ term. | |
| Nov 3, 2014 at 21:52 | comment | added | Fluctuations | @JerrySchirmer Is my Lagrangian wrong? I am totally confused? :( | |
| Nov 3, 2014 at 21:46 | comment | added | Zo the Relativist | Well, without the kinetic term, then your interaction term becomes a constraint (if you vary with respect to $\phi$), or it has an undetermined external function (if you don't vary with respect to $\phi$) | |
| Nov 3, 2014 at 21:28 | comment | added | Fluctuations | @JerrySchirmer Does it really have to have this kinetic term? I don't really know.. The problem didn't say there was a scalar field or something.. | |
| Nov 3, 2014 at 21:28 | comment | added | Fluctuations | @Prahar Pions are pseudo-scalar particles as far as I know and that's why I wrote the Lagrangian the way it is above. | |
| Nov 3, 2014 at 21:24 | comment | added | Fluctuations | @Prahar "Write the scattering amplitude for the process where pion particles are scattered off by Dirac particles" | |
| Nov 3, 2014 at 20:48 | comment | added | Prahar | @Fluctuations - I suggest that in the question, you copy down word-for-word the problem that you are struggling with and not your interpretation of it. Maybe then we can clarify your doubts. | |
| Nov 3, 2014 at 20:48 | comment | added | Prahar | @Fluctuations - Again, can you please tell me what scattering amplitude you are interested in? Is it an $e^- e^-$ scattering? or a pion scattering or a $e^+ e^-$ scattering? which one? | |
| Nov 3, 2014 at 20:33 | comment | added | Zo the Relativist | Aren't you missing kinetic terms for $\phi$ .? | |
| Nov 3, 2014 at 19:49 | comment | added | Fluctuations | @Prahar I am very confused, true. I am still struggling with this. My later aim is to find differential cross section for a process that has pions scattered off by Dirac particles. But first I write down the Lagrangian above and now I should find the scattering amplitude. I have searched long for feynmann rules for this theory but I still can't relate to my e- e- scattering case I learned back in class. Thank you a lot for you time!! | |
| Nov 3, 2014 at 18:33 | comment | added | Prahar | I think you are confused about the definition of the scattering amplitude. There is no such thing as the scattering amplitude of a theory. Rather, one defines a scattering amplitude for a certain scattering process in a certain theory. In your question, you have given us the theory - namely fermions coupled to a Yukawa scalar - but you have not given us the particular scattering process whose scattering amplitude you are interested in. Can you rephrase this question to include this? | |
| Nov 3, 2014 at 16:37 | history | edited | Nikos M. |
add tag feunam=-diagrams
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| S Nov 3, 2014 at 16:17 | history | suggested | Prof. Legolasov |
homework-and-exercises tag added
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| Nov 3, 2014 at 16:12 | review | Close votes | |||
| Nov 3, 2014 at 16:57 | |||||
| Nov 3, 2014 at 16:11 | comment | added | Fluctuations | @ACuriousMind I am aware of that, I just dont know how to deal with this problem since I can't relate this case to the e-e scattering nor to the e- p+ scattering. Just how to start? | |
| Nov 3, 2014 at 16:10 | answer | added | Prof. Legolasov | timeline score: 1 | |
| Nov 3, 2014 at 16:09 | comment | added | ACuriousMind♦ | "The" scattering amplitude does not exist. In general, one computes such amplitudes via Feynman diagrams. | |
| Nov 3, 2014 at 16:07 | review | Suggested edits | |||
| S Nov 3, 2014 at 16:17 | |||||
| Nov 3, 2014 at 15:54 | history | asked | Fluctuations | CC BY-SA 3.0 |