Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    Gold Member

    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...
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook