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

Running coupling

  1. Jul 4, 2013 #1
    First a little intro.

    The process of renormalization introduces in a QF theory a renormalization scale μ. Physical quantities do not depend on it, as a change of μ comes along with the change of the coupling g(μ) according to the RG law.

    But why then the physics can change so drastically along the RG trajectory? For instance, why asymptotic freedom in QCD is attributed to the unphysical ( μ,g(μ) ) RG behaviour? The μ is not introduced as the physical energy of a given process.

    Thanks
     
  2. jcsd
  3. Jul 4, 2013 #2

    Avodyne

    User Avatar
    Science Advisor

    Physics changes with the physical energy scale, not with μ. But if you choose μ near the relevant physical energy scale, and g(μ) happens to be small, then low orders of perturbation theory will give a good description of physics at that physical energy scale. If not, not.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Running coupling
  1. Running couplings (Replies: 1)

Loading...