Feynman Definition and 617 Threads

How can we demonstrate that the symmetries of S-Matrix can be applyed to parts of Feynman diagrams?The S-Matrix is the sum of infinite diagrams,why we know each or part of each diagram has the same symmetries as the symmetries of S-Matrix?

I read the Quantum Physics section of the online version of Feynman lectures http://feynmanlectures.caltech.edu/I_02.html#Ch2-S3 and I don't understand how he can deduce electron momentum from the Uncertainty Principle. I agree that the momentum is uncertain but how can he deduce that it is very...

I read the Quantum Physics section of the online version of Feynman lectures http://feynmanlectures.caltech.edu/I_02.html#Ch2-S3 and I don't understand the problem with the electrons "breaking away from the nucleus". So why can't the electrons just keep going in and out of the nucleus ?

Greetings, I think this will be a very quick thread. I am new to using Feynman diagrams, and have run into something that I find puzzling. The lowest-order Coulomb interaction Feynman diagram is (image from Wikipedia Moller Scattering article)...

Homework Statement I need to calculate <\phi(x_1)\phi(x_2)\phi(x_3)> and <\phi(x_1)\phi(x_2)\phi(x_3)>_{c} and then draw Feynman diagrams when \mathscr{L} = -\left(\left(\partial_{\mu}\phi\right)^{2} + m^{2}\phi^{2}\right) - g\phi^{3} through first order in g. Homework Equations...

Have you ever wished there was a high-quality up-to-date version of The Feynman Lectures on Physics available online? One that could be read with a browser so you could study FLP on your smartphone, tablet, notebook or desktop computer, whenever you felt like it? For free? Well, now there is...

Is there a list of matrix elements for elementary processes? ##f\bar{f}\to\gamma\to f^\prime\bar{f}^\prime## ##f\bar{f}\to Z^0\to f^\prime\bar{f}^\prime## ##ff^\prime\to W \to \ldots## ##qq^\prime\to \ldots## ##\ldots##

I have found an error in the QFT book by Mandl & Shaw, 2nd ed. In eqn (8.53), there is a minus sign in front of e^4. However, this cannot be justified on the basis of how the equation is derived. In the unnumbered eqn below eqn (8.52) there is a minus sign, and the trace in this eqn is to be...

I just Read arithemetic for the practical man and found really interesting...there's also Algebra for the Practical Man,Geometry for the Practical Man,Trigonometry for the Practical Man,Calculus for the Practical Man And everybody knows that the great feynman learned from these books...I would...

Apparently Bill Gates bought some tapes and released them to the public. I've been listening to them all day, and I'm enjoying the hell out of them. In lecture #2, the one on the relationship between mathematics and physics, he talks about how mathematics is the language of physics but that...

"Feynman" of Chemistry? Does anyone know if a chemistry book exists akin to Feynman's fundamental physics books?

I am learning QFT from Srednicki's book. However, in Figure 9.2 Srednicki has given all connected diagrams with E=0 and V=4. Are there any way to know the disconnected diagrams? Can you tell me what they are.

I have a request for some explanation in Feynman diagram concerning repelling/attraction of electrical charges. I have been told that when two charges (say, e1(-) and the e2(-)) repel each other, a photon is being emitted from one of them, and the other charge is later being hit by this photon...

Feynman Parameters--Peskin&Schroeder 6.44 I'm having some trouble deriving equation 6.44 on p.191 of Peskin and Schroeder (my book is the fifth printing, December 1997). The algebra comes close but I think that you need to do some arguing to actually get his answer--maybe this requires some...

In reading Ryder's book on quantum field theory he advocates reading off the Feynman rules directly from the Lagrangian in the path integral quantization method. I can sort of do this in phi-four theory, but it is not obvious in for example Yang-Mills theory, so I wondered if someone could...

Hi all Just a basic question really; I'm at university and have been tutoring someone through a couple of A level physics modules, and I'm covering some basic particle physics at the moment, which is all alright, but I've come to an issue with Feynman diagrams. Basically, for interactions...

Does anyone have a link or a reference to somewhere where these rules are explicitly derived for phi-four theory?

I'm trying to follow Feynman's explanation on page 26-10 of Volume 2 of The Feynman Lectures on Physics. He describes the electric and magnetic fields in a FoR S' moving between the plates of a condenser. Feynman writes that we see a reduced E and an added transverse B in S'. I've attached a...

Hi everyone. I have a very silly question. What is the Feynman rule for external legs of spin-zero boson? Is it just to multply by 1? Thank you

Hi guys! A serious doubt just passed through my mind. It is probably a silly question. In writing the Feynman rules for QCD, we know that the quark-gluon vertex is given by: $$-ig\gamma_\mu T^a_{ij}$$ where T is the SU(3) generator and i and j are the colors of the incoming and outgoing...

So apparently a neutral pion is a superposition of u\bar{u} and d\bar{d}. I'm having trouble understanding what this means. I have no problem understanding how the decay products of some scattering experiment could be a superposition of these two states, but how can we treat this superposition...

I've been doing some review of particle physics in Griffiths and I came across this statement that really didn't stand out to me before. "the idea is to draw all the diagrams contributing to the process in question (up to a desired order), calculate the amplitude (M) for each one, and add...

I've been given an action of S = -\frac{1}{2}m^2\phi^2 - \frac{\lambda}{3!}\phi^3 and the question then require drawing the feynman diagrams for the <\phi\phi> at order \lambda^2. I am told that there are 2 connected diagrams at one-loop order and one disconnected two-loop diagram and...

Hi all. I am new here but i decided to work a bit more and finish my diploma faster so i think i will use this forum more from now on. I was studing about quark color changes, quark interactions, gluons and generally the strong force. As i saw the Feynman diagrams i felt a bit confused...

I don't understand how the last equation in the attached picture is derived from equations 9.40 and 9.39, can anyone help?

Homework Statement Is the following reaction possible? If so, by what force? Draw (one of, if applicable)the lowest order Feynman diagrams for the process. n + n-bar --> ∏+ + ∏- + ∏0Homework Equations N/AThe Attempt at a Solution This process, it seems to me, should be possible. It...

Author: Richard P. Feynman, Robert B. Leighton and Matthew Sands Title: The Feynman Lectures on Physics Amazon Link: https://www.amazon.com/dp/0201021153/?tag=pfamazon01-20 http://www.feynmanlectures.caltech.edu/ (free) Prerequisities: Contents:

As per the Wheeler Feynman absorber theory, there cannot be electromagnetic radiation without an emitter and absorber. If we had only a single electron in the universe then disturbing it (accelerating it) would not produce any radiation since there was nothing to absorb it. Hence it would...

Hi Guys. I'm hoping that you might be able to help me out with a question I have about anti-particles in Feynman diagrams. I'm drawing these again for the first time in over a decade because I'm teaching an elementary physics course that requires the students to draw diagrams for a few...

I know this is an odd topic. The Feynman Lectures seem to be universally acknowledged as a great way to learn and grasp some of the simplest and most difficult concepts in physics. I am almost done the first volume and I really am enjoying the lectures. The odd thing is, I can't put my finger on...

Would it just be the same as with two electrons? (or any other pair of particles with the same charge) I'm kinda in two minds, I suspect that is wrong because wouldn't the fact that they attract each other (instead of repelling) means that the diagram would be drawn differently?

Feynman diagrams from "Quarks and Leptons" Halzen and Martin? The following scan is from Quarks and Leptons: An Introductory Course in Modern Particle Physics, Francis Halzen (Author), Alan D. Martin (Author), page 9. Can I take anything from the topological difference between figure (b) and...

What is it about the Feynman lectures on physics? Everywhere I hear about them they're refer to as great, awesome for science and what have you. But what makes them so revered? What sets them apart from say the Suskind Lectures or MIT OCW? Perhaps I am to young in my career to have learned...

There is a lot books written by Richard P Feynman. but Which one deals with his original work. I want to read that.If you have already read that then give some description also. Recently I read Maxwell Treatise on E&M. Book is Great but not readable for me.

1. The Problem I am trying to find the feynman rule which corresponds to the addition of an interaction term to the QED lagrangian which couples the electromagnetic field to a neutral massive vector boson field. In this problem, $$k^\mu$$ corresponds to the photon 4-momentum and $$q^\mu$$...

Alright, this is a pretty low level / silly question but I am having some issues. I would like to get the vertex rule for an interaction that has a field tensor involved like this... \partial_\mu Z_\nu -\partial_\nu Z_\mu do I treat the two Z's as separate fields? For a generic field...

Hello, I am trying to compute feynman diagrams with the feynman rules but I encounter some difficulties... Since the gamma matrices, spinnors, etc do not comute, the ordering of the different factor from feynman diagram has an importance. Is there some rules that say where to begin and in...

Homework Statement I am asked to draw a feynman diagram of K^- \rightarrow \mu \nu Homework Equations K^- consist of s\bar{u} The Attempt at a Solution I wonder what the direcion of the arrows should be, my guess is something like the attached image. edit: Ah, where the left u shoudl be an...

If a Feynman diagram only involves bosons, then can you multiply all external 4-momenta by negative one, and still get the same amplitude? Looking at the Feynman rules this seems true. If the diagram has a fermion (as real or virtual particle), then it seems this is no longer true. I just...

I need to put some Feynman Diagrams in a paper that I'm writing on my Mac (Lion) with Texpad, but I don't know how to create them in Latex (I tried it with some things I found on google [feynmf], but it didn't work). So I need a way to create them online, if you know one. I hope this is the...

I'm reading something which highlights the Feynman rules for QED, and it talks about what happens if you go along a fermionic line. For example this picture: http://wikipremed.com/image_science_archive_68/010601_68/170750_298px-ComptonScattering-u.svg_68.jpg According to these notes, there...

Hi, I live in the U.S. right now, but in a few months I'll be moving to another country. It will be much harder to get books like the Feynman lectures there, so I was wondering if I should get them now (or even at all). How good are they? Are they very difficult? How advanced should I be in...

Hey, I was wondering what exactly a loop is of this kind : I understand the initial & final four momentums to be the same and so there is no boundary on the possible allowed momentums in the loop. My professor said the loop is equal to (or can be modeled as) the self-interaction by...

Hey again, I have a question on a couple of things related to feynman diagrams but also the relativistic scalar propagator term. First of all, this interaction: The cross represents a self-interaction via the mass and characterised by the term: -im^2, is this just some initial state...

The diagrams aren't coming through on my system, but the text is readable: http://books.google.com/books?id=hlRhwGK40fgC&pg=SA13-PA6&lpg=SA13-PA6&#v=onepage&q&f=false First off, I'm pretty sure he re-uses ##\rho_\omicron## to mean different things at different points in the discussion...

Last year I got volume 1-3 of the Feynman lectures but as a soon mathematics major I think it'd be appropriate to read more mathematics lectures (and more enjoyable). Is there anything similar I could ask for for my upcoming birthday? Thanks,

I've noticed that Feynman appears to have incorrectly used the chemist's version of the ideal gas law. In eq. 39.23 he states it correctly: PV = NRT Pressure * Volume = Number of moles * Universal gas constant * Temperature Universal gas constant is R = N_{\omicron} k = Avogadro's...

Hello all . In feynman diagram horizontal direction is space . is that mean distance between particles ? is that means two electron must be near a certain distance to create a virtual photon ? Does one electron in Earth send electromagnetism force to one electron on moon by virtual photon ...

The figure 11-7 in Vol I of The Feynman Lectures appears incorrect to me. The second full paragraph explains exactly why it is incorrect. The caption should probably make it clear that the diagram represents the flawed depiction the author is warning against. Do others agree with this? If...

Hi all, I'm just getting started on particle physics and I have a few foolish :shy: questions about drawing feynman diagram. First, when do we draw the gauge bosons(such as W) vertically rather than horizontally through time? Second, can we always replace mediator photon by Z boson...