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Adjust parameters of Standard Model so only photons, e-, e+ remain?

  1. Feb 23, 2014 #1
    Could you have a hypothetical universe with only photons, electrons, and positrons by adjusting the parameters of the Standard Model to eliminate all the "other" stuff?

    If so is String Theory flexible enough to model a hypothetical universe with only photons, electrons, positrons, and Einsteins General Relativity?

    Are the vibrating String Theory strings that represent a quark more complex in some sense then the String Theory strings that represent an electron?

    Thanks for any help!
  2. jcsd
  3. Feb 24, 2014 #2


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    String Theory is a mathematical framework that, to date, has failed to make contact with the Standard Model or any portion of it. In fact, no one has succeeded in taking a String Theory model and calculating what particles it contains.
  4. Feb 24, 2014 #3


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    String theory indeed has some indications of particles it contains. The problem of it, is that it contains way too many particle states than we have encountered...at least that's what I know.

    As for the other particles, why do you ask that?
    For example we know that we have mixing in quarks through the CKM matrix and this implies that we need at least 3 generations of quarks (which also allows us to insert the CP violation we observe).
    A Standard Model missing quarks/gluons would lead in a world without strong interactions...The same I could say for the weak interactions....

    The electrons/positrons can of course exist in a model, as well as the U(1) generators corresponding to photons, but the U(1) group is an abelian group and thus it cannot somehow absorb the extra information coming from non-abelian groups as SU(n)s
    Last edited: Feb 24, 2014
  5. Feb 24, 2014 #4


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    This model is called quantum electrodynamics. You just have to add electrons and positrons as particles.
  6. Feb 24, 2014 #5
    I wondered if trying to explain something simpler (like electrodynamics + relativity) might make the problem a bit easier?
  7. Feb 24, 2014 #6

    Vanadium 50

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    Since part of the goal of string theory is to reproduce the correct particle content of the SM, asking it to come up with a simpler but wrong particle content seems counterproductive.
  8. Feb 25, 2014 #7


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    I think it would be an interesting step if the result is consistent with QED (or even QED+gravity).
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