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Beginner: Strings and space-time supersymmetry

  1. Oct 11, 2006 #1
    I was wondering, OK it is a gedakenexperiment because it is beyond
    observation, but... how is space-time supersymmetry (no worldsheet
    susy) supossed to appear from the point of view of states of the
    fundamental string? Do we observe entities with spin 0 and spin 1/2
    having the same mass? And what happens for highly excited levels of the
    string? If they mimic the QCD string, these excited levels have higher
    spin. Do we have multiplets for, say, Spin 10 and spin 10 +- 1/2 ? Do
    all these particles follow regge trajectories?

    [Moderator's note: Yes, Alejandro, spacetime supersymmetry also has an
    action on the worldsheet. Its existence is manifest in the Green-Schwarz
    formalism - see chapter 5 of Green-Schwarz-Witten - while its existence
    depends on seemingly miraculous identities such as Jacobi's obscure
    formula - see chapter 4 of Green-Schwarz Witten. You can also see the
    beginning of 2nd volume of Joe Polchinski's textbook, or many other
    sources. Yes, spinning modes of the string with an arbitrarily high
    spin have their superpartners whose spin differs by +-1/2 - or up to
    +-2 in the case of maximal supersymmetry. Such superpartners lie
    on the same Regge trajectory moved by +-1/2 or +-2 in the J direction.
    Only one of these trajectories is really "leading" - one with maximal
    J. Best wishes, LM]
  2. jcsd
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