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Help in clearing up Higgs boson/field

  1. Aug 11, 2011 #1
    I've had people explain this to me and I've watched a few videos but I'm still confused.

    Particles interacting with the 'Higgs field' gives them mass, but how much they interact with the field is determined by the mass of the particle in the first place. That doesn't seem to make sense so surely I'm mistaken :smile: can someone please explain it?
     
  2. jcsd
  3. Aug 11, 2011 #2
    Not sure what you mean here. The particles don't have mass 'in the first place', that's why they need to get some through interacting with the Higgs field. I guess pointing you to this wiki on yukawa interactions isn't going to help too much but here:

    http://en.wikipedia.org/wiki/Yukawa_interaction

    The point is that there is a coupling constant which determines 'how much' the massless particles interact with the higgs field (the 'g' in the first equation on the wiki, these are the Standard Model Yukawa couplings), but when that higgs field adopts a vacuum expectation value (i.e. becomes a constant) the same interaction term suddenly looks the same as a term which determines mass. The mass of the particle is then determined by a combination of the original coupling strength and the higgs VEV.

    It is a little bit more complicated than that actually but I think that is the basic gist of it.

    edit: Perhaps I'll say just slightly more. Before the higgs field adopts a VEV* all particles have no mass**, so this interaction with the higgs field looks pretty much like any any other particle interaction, i.e. there are real higgs bosons flying around and the massless particles scatter off them with a strength governed by their yukawa coupling. This picture changes completely once the universe cools so much that there are no more 'real' higgs bosons flying around, and the higgs field just becomes this constant flat nothing field***.

    *i.e. at high energies above the scale at which the electromagnetic and weak interactions unify.
    **we are above the confinement scale here so there are no hadrons, the universe filled with a crazy quark-gluon plasma, and the quarks are massless.
    ***the higgs field is very strange in this way. All the other fields, if you just let them settle to their ground state (i.e. all the particles go away), leave you with basically nothing (except some quantum fluctuations). The higgs field has a ground state which is non-zero, and so still matters a lot, i.e. it is not really 'nothing'. It is really weird.
    ****Please correct anything stupid I may have said :).
     
    Last edited: Aug 11, 2011
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