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How to solve the Free Parameter Problem in SUSY ?

  1. Mar 26, 2009 #1
    How to solve the Free Parameter Problem in SUSY ??

    In Standard Model, we have 19 free parameters:

    me Electron mass 511 keV
    mμ Muon mass 106 MeV
    mτ Tauon mass 1.78 GeV
    mu Up quark mass () 1.9 MeV
    md Down quark mass () 4.4 MeV
    ms Strange quark mass () 87 MeV
    mc Charm quark mass () 1.32 GeV
    mb Bottom quark mass () 4.24 GeV
    mt Top quark mass (on-shell scheme) 172.7 GeV
    θ12 CKM 12-mixing angle 0.229
    θ23 CKM 23-mixing angle 0.042
    θ13 CKM 13-mixing angle 0.004
    δ CKM CP-violating Phase 0.995
    g1 U(1) gauge coupling () 0.357
    g2 SU(2) gauge coupling () 0.652
    g3 SU(3) gauge coupling () 1.221
    θQCD QCD Vacuum Angle ~0
    μ Higgs quadratic coupling Unknown
    λ Higgs self-coupling strength Unknown

    Note that We have even more (above 100) free parameters in Supersymmetric Models while we solved another problems of SM (hierarchy problem).
    Is there a way to solve this problem in SUSY??
  2. jcsd
  3. Mar 26, 2009 #2
    Re: How to solve the Free Parameter Problem in SUSY ??

    Yep. You embed your SUSY into a string theory and replace your 100 free parameters with a discrete choice of one of [tex]10^{500}[/tex] false vacua. Unfortunately, at the present time it's unknown whether any one of them reduces to SM. But the number of possibilities is so huge that you can probably find any combination of constants in there.
    Last edited: Mar 26, 2009
  4. Mar 26, 2009 #3


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    Re: How to solve the Free Parameter Problem in SUSY ??

    Actually, depending on some specifics of the model, supersymmetry basically only adds a few extra degrees of freedom (for instance 5). The immense majority of the rest ~100 are contained in the soft breaking sector of the lagrangian and is more a phenomenology problem than a theoretical one, since we don't know how supersymmetry breaking actually occurs and must effectively parametrize our ignorance. If we had an accelerator that could probe the full SUSY parameter space, we'd find relationships between all those 'free' parameters and be able to pin down exactly how the breaking is accomplished.
  5. Jun 12, 2009 #4
    Re: How to solve the Free Parameter Problem in SUSY ??

    I heard that some of mSugra extensions reduce almost 100 free parameters to 5!
    I wonder what these numbers are and how can one reduce such a huge number to only 5??
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