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I Instability of the Higgs particle

  1. Aug 2, 2016 #1
    In the multiverse paradigm, the Higgs particle is said to be unstable. What does the instability of the Higgs particle mean? Could it spontaneously disappear? What are the conditions for something like that to happen? And what would be the fate of the universe if that were to happen - keeping in mind that neutrinos do not require the Higgs particle for their mass?
     
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  3. Aug 2, 2016 #2

    mfb

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    What do you mean by "multiverse paradigm"?

    The Higgs boson is unstable in all reasonable models. It means the particle decays to other particles, e. g. two quarks or two photons. Particles cannot simply disappear as energy and momentum have to be conserved.
    It does happen. I wrote an insights article yesterday concerning the experimental part of it.
     
  4. Aug 2, 2016 #3

    Orodruin

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    I strongly suspect the OP is confusing the stability of the Higgs boson with the stability of the Higgs vacuum.

    Apart from what mfb told you about the Higgs, neutrinos is the only fundamental fermion that is not necessarily getting its mass from the Higgs field ... You also need to separate and understand the differences between the Higgs field, the Higgs boson, and the Higgs vacuum.

    Also, please provide references to where your statements are taken from. Otherwise it is impossible for us to tell if it is a bad reference or if you have misinterpreted it or to help you understand it.
     
    Last edited: Aug 2, 2016
  5. Aug 2, 2016 #4
    Yes, I just happened to finished reading your insight article, when you posted the reply :oldsmile:. Please follow rest of my reply below.

    Concept of Higgs vacuum is new to me. How is it different from Higgs particle and Higgs field?

    I was trying to clarify what I heard in the documentary Particle Fever, which is about the discovery of the Higgs particle (It's on Netflix). One of the physicists mentioned that the Higgs particle is unstabe - he said this after the Higgs particle was discovered, and so I got the impression that maybe he meant it in a more fundamental way than the decay of the Higgs particle, which enables its detection.
     
  6. Aug 2, 2016 #5

    Orodruin

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    Can you give a reference to when in the documentary this statement is made? I am not going to look through all of it just to find the statement.

    The Higgs field is the fundamental entity - a quantum field. The Higgs vacuum is the lowest energy state of this field and it is the fact that it is non-zero that gives mass to the W and Z bosons as well as to the massive fermions through the Higgs mechanism. The Higgs particle is a quantum excitation around the Higgs vacuum - this is the particle that you observe the decays of in your detector.

    There is a possibility that the Higgs vacuum in which we are is not the global lowest energy state of the Higgs field, but rather a local minimum. If this is the case, there is the possibility of the Higgs vacuum to decay to the global minimum (or any local minimum which is a lower energy configuration for that matter).
     
  7. Aug 2, 2016 #6
    The buildup to the statement starts at 1:32:30

    By Higgs vacuum do you mean that which is related to the the Higgs vacuum of the inflationary universe, which was also in a local minimum, and which by some accounts may not have decayed entirely in the big bang universe, and may still be in a local minimum?
     
  8. Aug 2, 2016 #7

    vanhees71

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    The "vacuum" is just the ground state of a QFT. Here we discuss the Standard Model, and within the Standard Model the ground state is such that the Higgs field's expectation value in the vacuum state is non-zero. Due to Poincare invariance of the vacuum thie vacuum expectation value (vev) must be homogeneous and isotropic. Indeed within the standard model it provides all the fundamental masses to the matter particles through the coupling of the corresponding fields to the Higgs field (i.e., the lepton masses and the current-quark masses) in the Standard Model (let's not consider neutrino masses at the moment, which are already kind of "physics beyond the Standard Model").

    Note, however, that only about 2% of the mass of the matter around us is due to the Higgs mechanism. The remaining 98% of the mass is dynamically generated through the strong interaction, binding together quarks and gluons to colorless objects ("color confinement"). This is, however, a highly non-perturbative phenomenon and thus not really understood today. We, however, are pretty sure that it's the correct idea from lattice-QCD calculations which give a pretty accurate account of the mass spectrum of the known hadrons (mesons and baryons, among the latter protons and neutrons as the fundamental building blocks of the atomic nuclei building up the matter around us).
     
  9. Aug 3, 2016 #8
    So does the 2% of the mass generated by the Higgs mechanism consist of the mass of individual quarks and leptons?
     
  10. Aug 3, 2016 #9

    ChrisVer

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    It would be clearer to state this as that the higgs mechanism gives us a way to have massive quarks and leptons within the Standard Model.

    Now the matter around us does not have to be the sum of those individual particles since most of the times they appear in bound states... Within a bound state it doesn't really make sense to speak of the individual particle mass.... eg is the mass of the Hydrogen atom the same as the proton + electrons' masses? (no)... or in even more clear example: is the mass of the alpha particle (He nucleus) + Thorium230 the same as Uranium234 mass?
    also the rest of leptons apart the electrons don't exist for long times [muons and taus are unstable particles].
    SImilarily for on-shell quarks I guess.
     
  11. Aug 5, 2016 #10
    Thanks to all for the replies.
     
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