Feynman Diagrams are used to represent the fundamental forces by which elementary particles interact. In all interactions, time flows horizontally to the right.
a) Quantum Electrodynamics: An electron converts into an electron, with the emission of a photon (e → e + γ)
b) Quantum Chromodynamics: A quark converts into a quark, with the emission of a gluon (q → q + g)
c) Neutral Weak Interactions: Any lepton or quark converts into the corresponding lepton or quark, with the emission of a Z boson (f → f + Z)
d) Charged Weak Interactions for Leptons: A negative lepton converts into a corresponding neutrino, with the emission of a W- boson (l- → νl + W-)
e) Charged Weak Interactions for Quarks: A quark with charge -1/3 converts into the corresponding quark with charge +2/3, with the emission of a W- boson (q-1/3 → q+2/3 + W-)