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How Does The Electron Gain Its Mass

  1. Oct 13, 2014 #1

    bhobba

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    I started thinking about this in answering a question on the QM forum on getting the speed of light from QED. Its a massless boson so must travel at the speed of light. Then I recalled that bosons can gain mass from the Higgs so the real reason is the photon doesn't interact with the Higgs.

    But then it started me thinking - the electron isn't a Boson - so exactly how does it get its mass.

    Thanks
    Bill
     
  2. jcsd
  3. Oct 13, 2014 #2
    All fundamental fermions in the Standard Model get their masses from the Higgs mechanism (except neutrinos). There is a Yukawa coupling between each fermion field and the Higgs field, and when the Higgs field adopts a vacuum expectation value this generates an effective mass term for each fermion.

    See e.g. http://en.wikipedia.org/wiki/Yukawa_interaction#Spontaneous_symmetry_breaking
     
  4. Oct 13, 2014 #3

    bhobba

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    Thanks for the answer much appreciated.

    But do quarks gain their mass that way?

    I thought they got it from confinement? Or does some of it also come from the Higgs? If so how much?

    I am pretty sure I could Google the answer but sometimes sorting the truth from crank rubbish is a bit difficult.

    Thanks
    Bill
     
  5. Oct 13, 2014 #4
    Well certainly quarks have Yukawa couplings to the Higgs field exactly like electrons, and the top quark is the heaviest fermion because it has the largest Yukawa coupling, so it couples the strongest to the Higgs, which is why top quarks are important for Higgs physics. But I don't remember exactly what the correct thing to say regarding QCD contributions to quark masses is. Certainly there should be QCD corrections to quark masses. I think one gets into various difficulties because there are various ways to define what the mass of a quark "is", since we don't measure "free" quarks. Someone else will have to fill in the details here :).
     
  6. Oct 14, 2014 #5

    ChrisVer

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    Already answered.... The gauge bosons gain their mass because of the SSB and Higgs Mechanism.. The fermions gain their mass because of their yukawa coupling to Higgs field and Higgs field's vev and radiative corrections.
    All the gauge bosons interact with the Higgs field before the SSB. The photon is just a configuration of them which appears with zero mass eigenvalue (and corresponds to the remaining unbroken U(1) local symmetry).

    Quarks gain their mass that way. I am not sure about confinement, but it doesn't refer to quarks but to hadrons. The hadrons mainly gain their masses because of QCD radiative corrections.
     
  7. Oct 14, 2014 #6

    arivero

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    There is also a hand-waving argument about the minimum mass that a charged fermion should be expected to have in QED, from the self-energy, and it happens to be of the same order that the electron mass.
     
  8. Oct 14, 2014 #7

    bhobba

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    Ahhh. That jogged my memory - its not quark mass - its the mass of things like protons.

    Much appreciated.

    Thanks
    Bill
     
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