How to solve the Free Parameter Problem in SUSY ?

In summary, Supersymmetric Models have even more free parameters than Standard Model. However, it is unknown at present whether any of these extra parameters reduce to Standard Model.
  • #1
ophase
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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??
 
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  • #2


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 anyone of them reduces to SM. But the number of possibilities is so huge that you can probably find any combination of constants in there.
 
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  • #3


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.
 
  • #4


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??
 

1. What is the Free Parameter Problem in SUSY?

The Free Parameter Problem in SUSY refers to the large number of unknown parameters that arise in supersymmetric (SUSY) theories. These parameters are necessary to describe the symmetries and interactions in the theory, but their values cannot be predicted by the theory itself. This leads to a lack of predictability and makes it difficult to test the theory experimentally.

2. How does the Free Parameter Problem impact SUSY theories?

The Free Parameter Problem makes it challenging to test SUSY theories because the wide range of possible parameter values makes it difficult to make precise predictions. This can also lead to the problem of "fine-tuning," where certain parameters must be extremely precise in order for the theory to be consistent with observations. Additionally, the large number of parameters makes it challenging to determine which parameters are most important in explaining experimental data.

3. What are some proposed solutions to the Free Parameter Problem in SUSY?

One proposed solution is to find ways to reduce the number of free parameters in SUSY theories. This can be achieved through simplifying assumptions or by incorporating additional symmetries into the theory. Another approach is to use experimental data to constrain the possible values of the parameters and make more precise predictions. Additionally, some theories propose new physics beyond the Standard Model that could help explain the values of the parameters.

4. How are scientists currently addressing the Free Parameter Problem in SUSY?

Scientists are using a combination of theoretical calculations and experimental data to try and narrow down the possible values of the free parameters in SUSY theories. This involves performing calculations to predict the expected values of the parameters and then comparing these predictions to experimental data. If the predictions do not match the data, it may indicate that certain parameters are more important or that the theory needs to be modified.

5. What implications does the Free Parameter Problem have for the future of SUSY?

The Free Parameter Problem presents a significant challenge for the future of SUSY. If the problem cannot be solved, it could cast doubt on the validity of SUSY as a theory of particle physics. However, many scientists remain optimistic that with continued research and advancements in technology, the Free Parameter Problem can eventually be overcome and SUSY theories can be tested and validated.

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