Diagrams Definition and 689 Threads

It is my understanding that the task of enumerating all of the divergent diagrams in a quantum field theory can be reduced to analyzing a hand full of diagrams (well, at the moment I know that this is at least true for QED and phi^4 theory), and that all other divergent diagrams are divergent...

Hi. I'm self-studying particle physics.Just been looking at some questions where a reaction is listed and the questions asks to draw a Feynman diagram for the reaction and state which force is involved. I have the answers but they all seem so random and I would like to know how to decide which...

I study ncert physics class 12. Is there any special way you rote learned all the diagrams and derivations? (for example they ask in board exam that explain the working and principle of cyclotron and draw its diagram. Very hard to remember.)

I need help with 2.43 Is there any way to solve 2.43 without drawing the diagram again? And if I must draw another diagram, will I have to guess and check the length of the vectors since all the vectors are equal?

I'd appreciate it very much if someone told me if there is any free software to (draw and) calculate the amplitudes of simple (tree and one loop) Feynman diagrams. I'm hesitating because I don't know if this is the right place to ask. If it's not, I apologize in advance.

I'm studying Quantum Field Theory and the main books I'm reading (Peskin and Schwartz) present Feynman diagrams something like this: one first derive how to express with perturbation theory the n-point correlation functions, and then represent each term by a diagram. It is then derived the...

I am trying to figure out the Feynman diagrams for the Hierarchy problem. Here's what I have. (a) is the Higgs self interaction (φ4). It is quadratically divergent with additional logarithmic terms. (b) is the 1 loop Yukawa correction to the Higgs where F might be the top quark and g is...

Hello to everyone, I am an undergrad mechanical engineering student. Currently in 4 semester. I have this one major problem. I cannot memorize facts and diagrams. We have this subject, production technology, which consists of lots and lots of facts and for me an overwhelming amount of...

I am looking for a free online-resource sketching i) the way from Lie algebras to root systems and classification via Dynkin diagrams and ii) back to the Lie Algebra via reconstruction based on the information encoded in the Dynkin diagram. I would prefer a short PDF or web page, not a huge...

Homework Statement Homework Equations [/B] Shear force is calculated at each point on the beam. Downward forces are negative, upward forces are positive. Moments about points are calculated as force multiplied by perpendicular distance. Clockwise moments are negative. Anti clockwise...

Consider the scattering process ##W^{+}W^{-} \to W^{+}W^{-}##. This process is mediated in the Standard Model by 1. a four-##W## scattering, 2. ##Z##-boson exchange, 3. Higgs exchange...

What happens to one of the components when it is at VERY low concentration in a two component alloy? My problem: Uranium decays to thorium. The thorium isotopes it decays to typically have pretty short half lives. During casting, it is well known that thorium fractionates to the slag, crucible...

Homework Statement A 500-N person stands 2.5 m from a wall against which a horizontal beam is attached. The beam is 6 m long and weighs 200N (see diagram below). A cable attached to the free end of the beam makes an angle of 45 degrees to the horizontal and is attached to the wall. Homework...

Hello everyone, I am currently trying to understand how we can use feynman diagrams to estimate the matrix element of a process to be used in fermi's golden rule so that we can estimate decay rates. I am trying to learn by going through solved examples, but I am struggling to follow the logic...

The decay processes of the ##W## bosons are completely governed by the charged current interaction terms of the Standard model: $$\mathcal{L}_{cc} = ie_{W}\big[W_{\mu}^{+}(\bar{\nu}_{m}\gamma^{\mu}(1-\gamma_{5})e_{m} + V_{mn}\bar{u}_{m}\gamma^{\mu}(1-\gamma_{5})d_{n})\\...

I would like to draw the one-loop diagrams for four photon Delbruck scattering amplitude in QED. Here are the three one-loop diagrams that contribute to the scattering amplitude. There are three more one-loop diagrams that contribute to the amplitude. However, I cannot find the other...

One-particle irreducible diagrams are diagrams that cannot be broken into two disconnected diagrams by cutting an internal propagator.1. Why are the external lines on an one-particle irreducible diagram truncated/amputated? 2. What is the motivation for the word 'one-particle' in the terminology?

I am a little bit confused on how commutative diagrams show equality of two morphisms. For example, one can imagine the diagram for hf = kg, where composing f and g is the same morphism as composing h and k: https://upload.wikimedia.org/wikipedia/commons/9/91/Commutative_square.svg Why does the...

Homework Statement This question is just for b) "Calculate the force acting on the object indicated in the diagram." Homework Equations √ F12 + F22 = net force c2 = a2 + b2 -2ab cos A[/B]The Attempt at a Solution [/B] So I first started by using a technique my friend taught me to find...

I have some difficulty understanding how to go about with this problem: I came up with several graphs, you can see them in the attached picture (they are up to ~g^4 order). I am not sure about the self-interaction diagrams, but I think they are considered in the connected graphs (they are not...

In order to compute the scattering probability that two particles of type 1 (associated to ##\phi_1(x)##) which come from the far past with the momenta ##p1## and## p2##, to scatter and evolve into two particles of type 2 (associated to ##\phi_2(x)##) with the momenta ##p3## and ##p4## , I am...

I am currently undertaking a module in Failure Analysis, one topic of which is vibration monitoring of bearings. During this study, the notion of first and second Kerr diagrams as a tool for analysis came up. I have been trying to find additional information on Kerr diagrams; however, outwith...

Hello everyone, I am trying to compute the ΔF=2 box diagrams in SUSY with gluinos. The relevant diagrams are the following: I want to use the Dirac formalism and NOT the Weyl one. So, the only reference that I have for Feynman rules with Majorana spinors is the old but good SUSY review from...

Instead of uplading a picture, i want to draw a circuit diagram or some kind of a diagram and upload it to PhysicsForums, is there a way to do that?

What I would have to study before reaching the subject treated by Feynamn Diagrams? Is it too beyond the subjects treated in books like Shankar, Mc Intyre, Griffiths, etc? (I'm sorry for my poor English.)

Homework Statement Three charges, q1, q2, and q3, lie in a plane, as shown below. Find the net force on charge q2 (please refer to attachment for diagram) Homework Equations F= k x q1q2/R^2, knowledge of trig functions and separating x and y components The Attempt at a Solution So I found the...

Homework Statement Referencing to the gross and fine structure, explain how the energy diagrams differ for Hydrogen and Sodium. What effect does this have on the observed spectra? Homework Equations Sodium config: 1s21s22p63s1 Hydrogen : 1s1 The Attempt at a Solution I think that the diagram...

Consider the process of electron-positron annihilation into muons as given by $$e^{+}e^{-}\rightarrow \mu^{+}\mu^{-}.$$ The Feynman diagrams for this process to lowest-order are given by This is an s-channel diagram.Why are there no t-channel or u-channel diagrams for this process?

Free body diagrams are where you simplify each object to a point and draw all of the forces acting upon it. I am having difficulty understanding it entirely and it would really help to just have a bunch of examples of free body diagrams. If you have a link to a bunch that would be great. I...

Hi! I have been doing some reading over the past 5 months on spacecraft dynamics and physics mechanics -dynamics . I want to create figures and diagrams such as those found in Orbital Mechanics by Curtis, Vector Mechanics for Engineers by Beer and University P|hysics by Young. Which software...

Homework Statement An observer on the bridge of a spaceship is undergoing a proper acceleration a, so that the observer’s worldline expressed in terms of the coordinates of an inertial reference frame S is given by t(\tau)=(c/a)\sinh(a\tau/c)x(\tau)=(c^2/a)\sinh(a\tau/c) (a) Draw on a spacetime...

I'm looking for a website like this http://etn.io that allow me create my own diagram. Someone know?

Back again. This time I'm looking to build a small catalog of Feynman diagrams for my own use (and when I'm done to put it on the Internet in PDF format). I need your help to get a list of URLs together that I can download the required PDF's off the internet, bring them into Illustrator and have...

Homework Statement A positive charge Q1 = 7.4 μC is located at a point X1 = -2 m, a negative charge Q2 = -9.7 μC is located at a point X2 = 3 m and a positive charge Q3 = 2.1 μC is located at a point X3 = 9 m. Draw free body diagrams for the electric force acting on Q1, Q2 and Q3. Find the...

Hello - I just starting out in chemical engineering. I hold a batchelor's degree in Chemistry, and am making a transition to ChemE. This isn't for any class, just in general for reference, does anyone know of a good book that is primarily just thermodynamic charts, like T-S diagrams? I have...

I'm reading Srednicki's Quantum Field Theory. I 'm trying to read Srednicki's presentation of Feynman Diagrams in the chapter Path Integral for the Interacting Field Theory. Link to the book: The path integral for the phi-cubed theory is equation 9.11 in the book. Please read that. I get the...

So I'm fairly new to them and I was wondering about the reasons it is used so extensively. It'd be great to have a discussion on its significance in various applications. When exactly did people start using these diagrams? How is it used in various parts of physics. What all information can it...

Homework Statement The chain comprising three rings (each of mass ##0.25kg##) is suspended from a massless rope, and a pulling force ##\left(F=9N\right)## is exerted upwards on the rope. Picture: http://i.imgur.com/xeaiBsc.jpg?1. I need to find the values of all the unknowns. Homework...

Homework Statement http://www.mathalino.com/reviewer/mechanics-and-strength-of-materials/solution-to-problem-624-moment-diagrams-by-parts First , 1st solution, the author taking moment about 2m from A? secondly, the 800Nm is clockwise moment, so it is positive? why the 2400Nm on the...

According to Tong there are two Feynman diagrams for nucleon-nucleon scattering in the interaction of the complex and real scalar fields, but I can draw another diagram where the p1 and p2 particles enter a vertex and the p1' and p2' particles go out of another vertex (linked to the first one by...

A new entry for Physics Forums Insights has been posted https://www.physicsforums.com/insights/spacetime-diagrams-light-clocks/ For now, please use this thread to comment.

Hi, I want to draw Use Case Diagram using Dia. I found a tutorial for Class Diagrams " BUCKNELL UNIVERSITY CSCI 204 – INTRODUCTION TO UML DIAGRAMS IN DIA BY KATIE HEISE" But it does not deal with use Case diagram. Can some body guide me a to a tutorial in this regard? Zulfi.

Hi. I have seen quite a lot of demonstrations of time dilation and length contraction that used standard Minkowski diagrams WITHOUT any scales on the axes at all. If I understand them correctly they seem to directly compare lengths, which would imply (I think) that the scaling on the ##ct/x##...

Hello, Consider the the following Lagrangian of the $\phi ^4$ theory: $$\begin{align*} \mathcal{L} = \frac{1}{2} [\partial ^{\mu} \phi \partial _{\mu} \phi - m^2 \phi ^2] - \frac{\lambda}{4!} \phi ^4 \end{align*}$$ Now I'm interested in Feynman diagrams. 1. The second term gives the...

Homework Statement What is difference in shading between Argand diagrams containing inequalities with > and ≥ signs? Example Shade the appropriate region to satisfy the inequality |z|> 5 |z|≥ 5 The Attempt at a Solution I am aware of the fact that both will have circle centered at origin...

Hello there. I'm attending an introductory course in particle physics. We're supposed to know how to draw first-order tree level Feynman diagrams for simple reactions. I've been struggling to understand the method I should follow in order to correctly draw them. As I understand it now, we can...

Hello I encountered a problem in which it is specify that there are 2 time-ordered diagram for the s-channel for a certain process a+b->c+d. I understand that there is the one that can be associated with annihilation, but what would be a second one? Thank you!

Homework Statement Homework Equations 3. The Attempt at a Solution [/B] My confusion comes in with b/1, would it be going back to sigma inital since b/1=1? Also could someone explain what a finite state automaton is.

Consider a real scalar field described through the following lagrangian $$\mathcal L = \frac{1}{2} \partial_{\mu} \phi \partial^{\mu} \phi - \frac{1}{2}m^2 \phi^2 - \frac{g}{3!}\phi^3$$ The second order term in the S matrix expansion produces the diagrams in which we have a ##2 \rightarrow 2##...

I am working on a heat treatment plan, and I am curious if there is a go-to source for ttt diagrams for particular materials. I am working with SA-516 70, but it would be nice if there was one place where I could go to get current/reliable information. So far google searches have been unsuccessful.