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I Eletrons muons tau in string theory

  1. May 7, 2017 #1
    in string theory, where strings are posited as fundamental entities, what is the relation between eletrons muons tau

    how does string theory explain the increasing masses of leptons
    how do these leptons other properties come about in string theory
    what about the antiparticles of each? i.e positrons antimuons

    in a universe without a higgs field, does string theory distinguish massless eletrons muons tau and if so how?

    what prevents strings theory for also having a 4th and 5th and beyond generation charged leptons

    similar question for quarks and neutrinos.
  2. jcsd
  3. May 7, 2017 #2


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    Yes. I have wondered whether string theory (with its infinite number of "vibrational states") predict species beyond the (3 leptons for example) species we have observed.
  4. May 8, 2017 #3
    You're basically asking how does string theory reproduce the entirety of the standard model, as well as explaining something that the standard model doesn't explain (the number of generations, the pattern of masses)... which is OK, except that to understand the answer, first you need to understand how all those things work in the standard model, at the level of fields. In the standard model, all those particles are chiral fermions in representations of gauge groups, and (except for the neutrinos) they acquire mass through yukawa terms coupling weak singlets to weak doublets. That's how it works in string theory too, it's just all - done with strings. :-)
  5. May 8, 2017 #4
    thanks for reply, for now I'd like to keep it simple. in string theory where there is only strings as fundamental entities, what is the difference between eletrons muons tau ?
  6. May 9, 2017 #5


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    The most common expectation, where flavour is not a gauge group, is that they appear as topological effects in the manifold of hidden dimensions. Think for instance how over a torus you can draw two kinds of circles.
  7. May 9, 2017 #6


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    Allow me to put in a vote for "I don't know and neither does anyone else."

    The process of trying to build phenomenology out of raw string theory simply isn't there yet.
  8. May 9, 2017 #7
    the mass and properties of these charged leptons never change.

    are those topological effects in the manifold of hidden dimensions completely frozen for all eternity?

    so the 3 large spatial dimensions can warp and change in the presence of mass-energy
    but the hidden 6-7 dimensions are frozen and never changing?
  9. May 9, 2017 #8
    I thought there is only 1 fundamental entity, strings, which can be open or closed, characterized by 1 parameter string tension, and that different open string vibrations correspond to different particles.
  10. May 9, 2017 #9


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    Roughly speaking, the difference comes from different modes of string oscillations.
  11. May 9, 2017 #10


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    In principle, yes. But nobody yet found the vibrations which correspond exactly to the world we see.
  12. May 10, 2017 #11
    in what specific way does the modes of string oscillations in an electron differ from muon or tau?
  13. May 10, 2017 #12
    what prevents this from happening?
  14. May 10, 2017 #13


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    Nobody knows a precise answer.
  15. May 10, 2017 #14


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    The current understanding of non-perturbative string theory is actually very poor.
  16. May 11, 2017 #15
    In the stable configurations, the "cycles" in the hidden dimensions (like the paths around @arivero's torus) fill up with a "p-form flux" of virtual strings that create a stiff lowest-energy state of the geometry. The possible higher-energy states above this minimum then involve quantum excitations along the cycles. At very high energies there can be a jump to a different topology.
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