Difference between revisions of "Feynman Diagram"

Revision as of 18:56, 31 July 2019

Key Stage 5

Meaning

A Feynman diagram is a type of graph used to represent the interactions between subatomic particles.

About Feynman Diagrams

Feynman diagrams have time on the y-axis and space on the z-axis.

Feynman diagrams are used to simplify complex equations used to represent subatomic particle interactions.

Particles with a high velocity are seen as having shallow gradients 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 particle interaction.

The particles at the start of the equation are written at the bottom of the Feynman diagram while the products are written at the top.

\(p + e^-\)	\(p + e^- \rightarrow n + \beta^- + \bar\nu_e\)	\(p + e^- \rightarrow n + \beta^- + \bar\nu_e\)

The particles prior to the interaction are drawn first at the bottom of the Feynman diagram.	The particles after the interaction are drawn at the top of the Feynman diagram. It should be recognised that baryon conservation means a baryon becomes another baryon and lepton conservation means that a lepton is transformed from one type of lepton into another.	Finally the boson mediating the interaction is added as a wave between the two points of interaction. In this case a proton loses its positive charge therefore it is carried away to the electron via the W⁺ boson transforming the electron into an electron neutrino.

Examples


This Feynman diagram shows the electromagnetic interaction between two protons via the virtual photon.	This Feynman diagram shows the weak interaction in which a neutron decays into a proton. \(n \rightarrow p + \beta^- + \bar\nu_e\)

This Feynman diagram shows the weak interaction in which a proton captures an electron to become a neutron. \(p + e^- \rightarrow n + \nu_e\)	This Feynman diagram shows the weak interaction in which an up-quark decays into a down-quark, which is observed as a proton decaying into a neutron via beta emission. \(u \rightarrow d + \beta^+ + \nu_e\)

@@ Line 9: / Line 9: @@
 ===Constructing a Feynman Diagram===
-: '''Feynman Diagrams''' can be constructed from the equations representing a [[Subatomic Particle|particle]] [[Fundamental Interaction|interaction]].
+: '''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"
@@ Line 23: / Line 23: @@
 |[[File:FeynmanDiagramElectronCapture.png|center|200px]]
 |-
-| style="height:20px; width:200px; text-align:center;" |The [[Subatomic Particle|particles]] prior to the [[Fundamental Interaction|interaction]] are drawn first at the bottom of the '''Feynman diagram'''.
+| 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'''.
-| style="height:20px; width:200px; text-align:center;" |The [[Subatomic Particle|particles]] after the [[Fundamental Interaction|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.
+| 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.
-| style="height:20px; width:200px; text-align:center;" |Finally the [[boson]] mediating the [[Fundamental Interaction|interaction]] is added as a [[wave]] between the two points of [[Fundamental Interaction|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<sup>+</sup> boson]] transforming the [[electron]] into an [[Electron Neutrino|electron neutrino]].
+| 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<sup>+</sup> boson]] transforming the [[electron]] into an [[Electron Neutrino|electron neutrino]].
 |}