Why Don't SUSY Leptons and Quarks Exist Alongside Standard Model Bosons?

[orricl]

If susy really exist in nature, why does it not exist between leptons or quarks and gauge bosons such as photons, weak currents or gluons in the standard model?

 

[mfb]

What do you mean with "between leptons or quarks and gauge bosons"? That does not make sense.
Supersymmetry (if it exists) gives every particle a corresponding partner (a bit more in the Higgs sector). We know that all known particles are not supersymmetric partners of other known particles.

 

[arivero]

Supersymmetry (if it exists) gives every particle a corresponding partner

This is a twist of the English language I am never sure of: Does "a particle" mean "one particle", or "at least one"? Because of each Weyl fermion we get two scalars.

 

[mfb]

I don't want to go into details how to count particles, as I don't think it helps here.

 

[haushofer]

Because the supersymmetry forces you to consider multiplets with particles which differ by (steps of) spin 1/2.

 

[arivero]

Reading again the OP question, I think it asks for R-parity.

 

[haushofer]

Ah, ok. I would say that these fermionic superpartners of the gauge bosons must sit in the same rep. of the gauge group, namely the adjoint. This is because gauge transfo's commute with susy. But quarks and leptons sit in the fundamental rep.

 

[ChrisVer]

Reading again the OP question, I think it asks for R-parity.

You have a good sense of imagination if you interpreted that question as a question on "R-parity" ...
I think you can show that the susy algebra allows for an extension of U(1)-symmetry , whose generators follow certain algebra relations.
Also if I recall well, this extra symmetry can send some parameters in the Lagrangian to be very small to avoid e.g. proton decay with unreasonable lifetime...

 

[Vanadium 50]

We've got 7 messages guessing what the OP meant. He's been back several times since he posted his question. Since he hasn't clarified it, I'd guess he no longer is interested in it, so all this arguing about what he means is probably futile.

 

[ohwilleke]

Just for fun, I'll provide my reading of the OP:

I think the OP is asking, "why can't the Standard Model fundamental bosons be the superpartners of the Standard Model fundamental fermions?" The notion is that is supersymmetry is a symmetry between fundamental bosons and fundamental fermions. So, why don't the ones we have balance out without the need to hypothesize new sparticles to do the balancing.

The answer to that question is, that in SUSY the balancing is tautologically obvious which makes a variety of mathematical questions of broader concern in quantum physics much simpler. Any balancing between fermions and bosons in the Standard Model has cryptic origins that are not part of the Standard Model itself and are not understood at this time.