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Yang-Mills, QED, QCD and Yukawa theories

  1. Dec 7, 2014 #1
    What is the difference between Yang-Mills and QED theories? Yukawa and QCD? specially in terms of the lagrangians.

    I really want to get into this subject with a previously first sight.
  2. jcsd
  3. Dec 8, 2014 #2
    Yang Mills and QCD ( which is just a particular Yang Mills theory) are based on non abelian gauge symmetries while QED is based on abelian gauge symmetry.

    Yukawa theory doesn't have spin 1 particles, just fermions and scalars.

    However, this is a very general question. I would recommend that you study the subject ( which would take some effort) and come back with more specific questions.
  4. Dec 8, 2014 #3
    Why Yukawa focused on the search of the meson-neutron interaction?
  5. Dec 9, 2014 #4
    In what context? do you mean focused on meson-neutron and not meson-proton interactions?
  6. Dec 9, 2014 #5
    Nucleon* typo
  7. Dec 9, 2014 #6
    In the Yukawa theory, the meson nucleon interaction is the pillar of theory. The nucleon-nucleon interaction is mediated by meson exchange, which is present due to the meson nucleon interaction.
    The first and foremost prediction was that a meson with such properties exists, which was not known at the time the theory was published.
  8. Dec 9, 2014 #7


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    Why did he focus on the pion-nucleons? Because nucleons are fermions spin 1/2 particles while pions are scalar spin 0 particles.
    Of course the interaction Lagrangian would be an effective one, since it corresponds to energies lower than the QCD scale...
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