Diagrams Definition and 689 Threads

A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since ancient times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a three-dimensional visualization which is then projected onto a two-dimensional surface. The word graph is sometimes used as a synonym for diagram.

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  1. G

    A Divergent Diagrams in the Standard Model

    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...
  2. D

    I Confused about Feynman diagrams

    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...
  3. S

    Studying How do i learn derivations and diagrams?

    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.)
  4. Adhil

    MHB Solving 2.43: Drawing Diagrams & Vector Lengths

    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?
  5. C

    I Software for calculating Feynman diagrams

    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.
  6. L

    A How does one find the Feynman diagrams?

    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...
  7. N

    A Hierarchy problem and Feynmam diagrams

    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...
  8. Sanchayan Ghosh

    Studying How can I effectively memorize diagrams for my engineering courses?

    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...
  9. tom.stoer

    A From Lie algebras to Dynkin diagrams and back again

    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...
  10. DevonZA

    Draw the shear force and bending moment diagrams for beams

    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...
  11. S

    A Relative sign in diagrams for ##Z##-boson exchange for ##WW## scattering

    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...
  12. D

    Phase Diagrams at Very Low Concentration of one Component

    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...
  13. Janet1234

    Drawing free body diagrams (torque; rotational motion)

    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...
  14. S

    I Matrix Elements via Feynman Diagrams

    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...
  15. S

    A What Are the Possible Decay Processes of the W⁻ Boson?

    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})\\...
  16. B

    A One-loop diagrams of Delbruck scattering

    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...
  17. S

    A What Drives the Naming and Structure of One-Particle Irreducible Diagrams?

    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?
  18. Mr Davis 97

    I Commutative diagrams and equality of composition

    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...
  19. B

    Am I doing this right? (Physics, Newtons, Diagrams)

    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...
  20. ChrisVer

    A QFT phi3 Feynman diagrams and correlation function

    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...
  21. binbagsss

    I Scattering, 4 point correlator, number of distinct Feynman diagrams

    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...
  22. M

    Kerr Diagrams for Defect Frequencies

    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...
  23. T

    A Help with Feynman diagrams involving Majorana Fermions

    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...
  24. doktorwho

    LaTeX How do you draw diagrams on PhysicsForums?

    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?
  25. K

    I Study for Feynman Diagrams: Beyond Shankar, etc?

    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.)
  26. H

    Coulomb's Law in Two Dimensions

    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...
  27. P

    Explain how the energy diagrams for H and Na differ

    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...
  28. S

    A Feynman diagrams for ##e^{+}e^{-}\rightarrow \mu^{+}\mu^{-}##

    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?
  29. C

    Can you me understand free body diagrams

    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...
  30. Alexanddros81

    I How to draw figures and diagrams?

    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...
  31. A

    Worldlines and spacetime diagrams

    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...
  32. B

    Create Diagrams: Find a Website Like etn.io

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

    I Building a List of Feynman Diagrams

    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...
  34. C

    Electric Charge and Force free body diagrams

    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...
  35. E

    Book of T-S diagrams, or the like

    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...
  36. J

    A Srednicki's QFT: Feynman Rules and Feynman Diagrams

    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...
  37. otaKu

    I E-k Diagrams: Exploring Uses, History, & Facts

    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...
  38. K

    Free-body diagrams and Newton's laws with a suspended chain

    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...
  39. F

    Solution to Problem 624: Moment Diagrams by Parts

    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...
  40. carllacan

    I Diagrams for nucleon scattering

    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...
  41. robphy

    Insights Spacetime Diagrams of Light Clocks [comments]

    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.
  42. Z

    Use Case Diagrams (UML) using Dia

    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.
  43. G

    I Minkowski diagrams without scales on axes

    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##...
  44. N

    I Lagrangian and Feynman diagrams

    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...
  45. F

    Shading in Argand diagrams involving inequalities

    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...
  46. Xico Sim

    I Elementary processes in Feynman Diagrams

    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...
  47. S

    I S-Channel Process: a+b->c+d Diagrams

    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!
  48. Kingyou123

    Transition Diagrams and finite-state automaton?

    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.
  49. C

    I Feynman diagrams and the Wick contraction

    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##...
  50. Pattonias

    Go-to source for steel ttt diagrams?

    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.
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