Changes

A '''Feynman diagram''' is a type of [[graph]] used to represent the [[Fundamental InteractionInteractions|interactions]] between [[Subatomic Particle|subatomic particles]].

: '''Feynman diagrams''' are used to simplify complex equations used to represent [[Subatomic Particle|subatomic particle]] [[Fundamental Interactions|interactions]].: [[Subatomic Particle|Particles]] with a high [[velocity]] are seen as having shallow [[gradient]]s on a '''Feynman diagram''' since they travel a large distance in space over a short duration of [[time]]. ===Constructing a Feynman Diagram===: '''Feynman Diagrams''' can be constructed from the equations representing a [[Subatomic Particle|particle]] [[Fundamental Interactions|interaction]].: The [[Subatomic Particle|particles]] at the start of the [[Nuclear Equation|equation]] are written at the bottom of the '''Feynman diagram''' while the [[product]]s are written at the top.{| class="wikitable"|+[[Electron Capture]]| style="height:20px; width:200px; text-align:center;" |<math>p + e^-</math>| style="height:20px; width:200px; text-align:center;" |<math>p + e^- \rightarrow n + \nu_e</math>| style="height:20px; width:200px; text-align:center;" |<math>p + e^- \xrightarrow{W^+} n + \nu_e</math>|-|[[File:FeynmanDiagramElectronCapturePt1.png|center|200px]]|[[File:FeynmanDiagramElectronCapturePt2.png|center|200px]]|[[File:FeynmanDiagramElectronCapture.png|center|200px]]|-| style="height:20px; width:200px; text-align:center;" |The [[Subatomic Particle|particles]] prior to the [[Fundamental Interactions|interaction]] are drawn first at the bottom of the '''Feynman diagram'''. Both the [[proton]] and [[electron]] in this '''diagram''' are drawn with a steep [[gradient]] to show their relatively small [[velocity]] compared to the [[Speed of Light|speed of light]].| style="height:20px; width:200px; text-align:center;" |The [[Subatomic Particle|particles]] after the [[Fundamental Interactions|interaction]] are drawn at the top of the '''Feynman diagram'''. It should be recognised that [[Conservation of Baryon Number|baryon conservation]] means a [[baryon]] becomes another [[baryon]] and [[Conservation of Lepton Number|lepton conservation]] means that a [[lepton]] is transformed from one type of [[lepton]] into another. The [[Electron-neutrino|electron-neutrino]] in this [[diagram]] is drawn with a shallow [[gradient]] to show that it travels close to the [[Speed of Light|speed of light]].| style="height:20px; width:200px; text-align:center;" |Finally the [[boson]] mediating the [[Fundamental Interactions|interaction]] is added as a [[wave]] between the two points of [[Fundamental Interactions|interaction]]. In this case a [[proton]] loses its [[Positive Charge|positive charge]] therefore it is carried away to the [[electron]] via the [[W-boson|W⁺ boson]] transforming the [[electron]] into an [[Electron-neutrino|electron-neutrino]].|} {| class="wikitable"|+Neutron Decay| style="height:20px; width:200px; text-align:center;" |<math>n \rightarrow</math>| style="height:20px; width:200px; text-align:center;" |<math>n \rightarrow p + \beta^- + \bar\nu_e</math>| style="height:20px; width:200px; text-align:center;" |<math>n \xrightarrow{W^-} p + \beta^- + \bar\nu_e</math>|-|[[File:FeynmanDiagramNeutronDecayPt1.png|center|200px]]|[[File:FeynmanDiagramNeutronDecayPt2.png|center|200px]]|[[File:FeynmanDiagramNeutronDecay.png|center|200px]]|-| style="height:20px; width:200px; text-align:center;" |The [[Subatomic Particle|particles]] prior to the [[Fundamental Interactions|interaction]] are drawn first at the bottom of the '''Feynman diagram'''. The [[neutron]] in this '''diagram''' is drawn with a steep [[gradient]] to show it has a relatively small [[velocity]] compared to the [[Speed of Light|speed of light]].| style="height:20px; width:200px; text-align:center;" |The [[Subatomic Particle|particles]] after the [[Fundamental Interactions|interaction]] are drawn at the top of the '''Feynman diagram'''. It should be recognised that [[Conservation of Baryon Number|baryon conservation]] means a [[baryon]] becomes another [[baryon]] and [[Conservation of Lepton Number|lepton conservation]] means that if a [[lepton]] comes into existence there must also be an [[antilepton]]. The [[antielectron-neutrino|antielectron-neutrino]] in this [[diagram]] is drawn with a shallow [[gradient]] to show that it travels close to the [[Speed of Light|speed of light]].| style="height:20px; width:200px; text-align:center;" |Finally the [[boson]] mediating the [[Fundamental Interactions|interaction]] is added as a [[wave]] between the two points of [[Fundamental Interactions|interaction]]. In this case a [[neutron]] loses a [[Negative Charge|negative charge]] therefore it is carried away to produce the [[electron]] via the [[W-boson|W^- boson]] also producing an [[antielectron-neutrino]].|} ===Examples==={| class="wikitable"|-|[[File:FeynmanDiagramProtonProton.png|center|300px]]|[[File:FeynmanDiagramNeutronDecay.png|center|300px]]|-| style="height:20px; width:300px; text-align:center;" |This '''Feynman diagram''' shows the [[Electromagnetic Interaction|electromagnetic interaction]] between two [[proton]]s via the virtual [[photon]].| style="height:20px; width:300px; text-align:center;" |This '''Feynman diagram''' shows the [[Weak Nuclear Interaction|weak interaction]] in which a [[neutron]] [[Radioactive Decay|decays]] into a [[proton]]. <math>n \rightarrow p + \beta^- + \bar\nu_e</math>|-|[[File:FeynmanDiagramElectronCapture.png|center|300px]]|[[File:FeynmanDiagramUpDecay.png|center|300px]]|-| style="height:20px; width:300px; text-align:center;" |This '''Feynman diagram''' shows the [[Weak Nuclear Interaction|interactionsweak interaction]] in which a [[proton]] [[Electron Capture|captures]] an [[electron]] to become a [[neutron]]. <math>p + e^- \rightarrow n + \nu_e</math> | style="height:20px; width:300px; text-align:center;" |This '''Feynman diagram''' shows the [[Weak Nuclear Interaction|weak interaction]] in which an [[up-quark]] [[Radioactive Decay|decays]] into a [[down-quark]], which is observed as a [[proton]] [[Radioactive Decay|decaying]] into a [[neutron]] via [[Beta Particle|beta]]emission. <math>u \rightarrow d + \beta^+ + \nu_e</math> |}