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Can electro-weak unification be tested at CERN?

  1. Jan 16, 2016 #1
    1.- Electroweak interaction broke its symmetry about 1ps after the Big Bang and two different types of interactions appeared: weak interactions and electrodynamics.

    2.- The LHC at Geneva is routinely conducting experiments above the energy threshold of electroweak unification. Could these experiments reproduce (at a very small scale) the state the Universe was at 1ps after the Big Bang?

    3.- If so, have they foud any evidence of the massless right and left handed electrons? Have the found any evidence of the three massless W bosons and the massless B boson?

    4.- If not, can they? After all, there are no such fields in our frozen Universe. How could all these particles exist without the corresponding vacuum fields from which they could be brought into existence?
  2. jcsd
  3. Jan 16, 2016 #2
  4. Jan 16, 2016 #3

    Vanadium 50

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    Unification doesn't work this way. What unification means is that there is a set of forces (electromagnetic and weak) that can be described by a single set of equations with a single strength. This has been shown to be the case at many times and places, perhaps most elegantly by Hera:


    At low energies, there appear to be two different forces with two different strengths (the red and the blue), but at high energies they come together. That's unification.

    You seem to be talking about the electroweak phase transition, which happens at a very high temperature (probablly above 100 TeV) and it is a many-body problem. So not only does each individual particle need a lot more energy that the LHC can produce, you need a lot of them.
  5. Jan 16, 2016 #4


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    Isn't that the Goldstone boson equivalence theorem?
  6. Jan 16, 2016 #5
    Vanadium 50: I'm not sure if I understood you well. Do you mean that 'weak and electromagnetic interaction unification energy' roughly means that you need to use Weinberg's-Salam theory to achieve accurate results? and at much lower energies you could just use QED and Fermi's model?
    Vanadium 50: Did you also mean that 'electroweak phase transition energy' is the energy scale at which QED and weak force running coupling contants merge?
  7. Jan 17, 2016 #6
    Vanadium 50 doesn't seem to be available at the moment. Could anybody tell me if what I understood from his explanation is, at least, a rough simplification of what he actually said? I'm not even a physicist and even a crude aproximation would do for me.
  8. Jan 20, 2016 #7
    Current theory says that there is no "QED force" at all. There are two weak forces, one is due to weak isospin SU(2) symmetry, another is due to weak hypercharge U(1) symmetry. These forces have coupling constants g2 and g1. "QED force" is due to existence of linear combination of SU(2) and U(1) generators which leaves our vacuum invariant. This linear combination generates (another) U(1) group. Its coupling constant, "fine structure constant" is 1/4pi * (g1*g2)^2/(g1^2 + g2^2).

    Thus, "QED and weak force running coupling contants merge" doesn't even make sense, really.

    The transition energy is the energy above which masses of W and Z bosons are insignificant. At those energies, seeing QED/weak interactions as exchange of W+-,Z,gamma bosons is not a useful description. It would be simpler to see it as exchange of W1,W2,W3 and B bosons of original, unbroken symmetries.
  9. Jan 20, 2016 #8


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    I cannot read minds, but I guess he meant something like that.
  10. Jan 20, 2016 #9
    Thank you for your interest, mfb!
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