Feynman diagram Definition and 167 Threads

Lets say we have a process where: Particle B(P) -> v(p2) + k some particle effectively goes to an antifermion and a photon, with momentums P, p2, and k. And the diagram is just straightforward, in arrow to vertex, out photon and out antifermion from vertex. Now the arrow on the...

I always wanted to ask (but was afraid to) about the borders on the famous Feynman diagrams. As I understand, Feynman diagrams have the same age as Copenhagen Interpretation. So at that time it looked very logical: quantum behavior inside, but classical world outside. Outgoing particles are the...

Homework Statement Hello, I am trying to draw a Feynman Diagram at quark level for the decay sigma+ -> neutron + pi+.Homework Equations sigma+ -> neutron + pi+ uus -> udd + udbarThe Attempt at a Solution Well, the attachment is what I came up with. I have no idea if it's right to be honest...

Homework Statement I'm working my way through Quantum Field Theory in a Nutshell by A. Zee. I'm religiously doing the exercises but since I'm doing it on my own (I'm not in school) I have no one to ask when I get stuck. Any hints would be appreciated. The problem is IV.7.5, on page 253 of...

can someone please explain the attached picture to me? if the electron and positron are just annihilating each other shouldn't the positron be going the other way? and shouldn't the antiquark be going the other way too? and what's up w/ the ->t thing at the bottom?

Homework Statement Hello :smile: The question is from "Advanced Physics" by Adams and Allday. It is from section 9 "The Physics of Particles", "Practice Exam Questions". It is question 11, part c. The level of this study is between school and University. Figure 9.5 represents a simple...

Can anyone recommend a good Feynman diagram calculator ?

...like in Photon-Photon-scattering. I know this doesn't make sense physically but the value for the diagram should still be computeable. If I want to put the expression for the matrix element together, I get a matrix, but it should be a scalar, right? Since the spinor bi-product is missing...

Homework Statement Draw the Feynman diagram for: e^{-} + p \rightarrow n + \upsilon_{e} Sorry, I don't know how to make everything even but you should get the gist. Homework Equations The Attempt at a Solution Well, what I have is the electron and proton annihilating(and this...

Homework Statement Q) Neutral pion decays into 2 photons which then decay into electron-positron pairs. What would the feynman diagram look like? :confused:

is there any program that can generate the feynman diagram for a specific perturbation of n-order contributions to Green function?

Hi! I need some help with latex. I need to draw Feynman diagrams and it seems that the package feynmfm relies on Metafont, which I really don't even have the slightest idea as how to use it. Anyway, I tried to find a good tutorial on the subject (metafont) but it looks like i will need some...

I'm far from well versed in physics, but I'm trying to understand something about a Feynman diagram I saw. The diagram shows an electron and positron annihilating, and producing a quark/anti-quark pair and a gluon. I recently saw a special on the discovery channel that said matter/anti-matter...

Hi I have to draw a Feynman diagram for the following reaction: K^{*+} \rightarrow K^0 + \pi^+ The K^{*+}-meson is composed of an u and an anti-s quark, the K^0-meson is composed of a d and an anti-s quark, and the \pi^+-meson is composed of an u and an anti-d quark. I have drawn...

In doing my \phi^{3} theory I didn't know exactly how to count the number of loops in a diagram given the number of vertices, internal and external lines. Is there a general algorithm in doing this? What if we have more than one interaction vertex (e.g. the Standard Model)? PS. What does it...

I have been researching Feynman and his diagram and really can't find much on the Diagram itself. Could anyone tell me the mathematics and other concepts behind it in excruciating detail? Or at least a site I can find it? Thanks

I'm pretty new to the particle physics world, and modern physics in general, so bear with me. I also don't have a book yet, so it's kind of messed up I'm a bit confused by a few apsects of feynman diagrams, although my confusion actually lies much deeper. Looking at this diagram...