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How do we know which is strong,weak force with considering Lagrangian?

  1. Jul 17, 2011 #1
    Please teach me this:
    How do we know a force is strong,week or intermediate by considering the corresponding Lagrangian.It seem that the intensiveness depends on both coupling constant,the form of theory(form of Lagrangian).By the way, the mass of force carrier boson stipulates the range of the force. The greater mass the shorter distance of interaction.But there is an unclear for me,because the mass changes when we change transfer momentum as we know in renormalization group theory.
    Thank you very much in advance.
  2. jcsd
  3. Jul 18, 2011 #2
    At the moment,I think that four types of interaction are discovered by experiment.Each type of interaction has many characteristics.And each theory is self-consistent with those characteristics.But it seem that we could not say any thing about the intensiveness of force basing on the Lagrangian,because all Lagrangian have same form:(coupling constant)(boson field)(current of fermion fields).Is that correct?
  4. Jul 19, 2011 #3
    The week coupling constant g(of week interaction) has the same order as electromagnetic coupling constant(of QED),then I do not understand why the force of week interaction is very much weeker than electromagnetic force.
  5. Jul 19, 2011 #4
    It seem to me that the short distant interaction in general speaking must be the week interaction(when we consider ''macroscopic" level).
  6. Jul 19, 2011 #5
    With the meaning that the mass of force carrier boson is large.
  7. Jul 20, 2011 #6
    It seem to me that the SU(3) symmetry leads to large coupling constant at large distance and long distance interaction.Then the interaction must be strong interaction.
    The week and electromagnetic interactions have the same order of coupling constant,but the week interaction is short distance interaction beacause of massive boson,then the ''week interaction'' must be the week interaction when we consider ''macro'' level physics.
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