Are there scalar partners for the Z and W particles in massive SUSY multiplets?

[arivero]

Does anybody remember some reference to models where the Z and W particles are in massive susy multiplets of vector type?

Such models should predict, besides the zino and wino, scalar partners for the Z and W, as well as new chiral fermion for each (probably the later should be able to combine with the wino and zino).

And, does the MSSM predict such content too? Or is it different because susy breaks before than electroweak?

 

[blechman]

Does anybody remember some reference to models where the Z and W particles are in massive susy multiplets of vector type?

Such models should predict, besides the zino and wino, scalar partners for the Z and W, as well as new chiral fermion for each (probably the later should be able to combine with the wino and zino).

And, does the MSSM predict such content too? Or is it different because susy breaks before than electroweak?

so you want to embed the gauge sector into an N=2 susy theory? There are plenty of suggestions to do this (including a few published by yours truly! just look for references to "Dirac Gauginos"). MSSM has a purely N=1 content, so the vector bosons are part of a massless vector multiplet (Majorana gauginos), and they get mass from the N=1 Higgs multiplet, just like the usual SM.

 

[arivero]

MSSM has a purely N=1 content, so the vector bosons are part of a massless vector multiplet (Majorana gauginos), and they get mass from the N=1 Higgs multiplet, just like the usual SM.

It seems that people is biased because normally you first break supersymmetry and then later you break electroweak symmetry. But you can first break electroweak symmetry and still kept supersymmetry, leaving for a next step its breaking.

And then, independently of the mechanism of electroweak symmetry breaking, the pure N=1 massive vector multiplet contains a massive vector, four fermionic components, and one scalar. Is the only way you can build a massive multiplet in N=1. In fact it is in the first pages of the textbooks I am reading now (Terning's).

Of course, when the mechanism of electroweak symmetry breaking is the higgs, the scalars are higgses (just as the zero helicity state is also a higgs eaten by the vector). But I am interested in the agnostic case and how far can one go with it.

Hmm are you telling me that the N=1 massive case is equal to the N=2 massless?

 

[arivero]

In any case, the first question that is perturbing me now is, has this Dirac Gaugino all their four components with the same electric charge?

 

[blechman]

I am confused by your accusation of "bias" (although I see you rewrote the statement...). I am only defining the "MSSM" (emphasis on the first M = MINIMAL).

So the first criticism to your suggestion is that if SUSY is broken at a scale below the weak scale, then we should see SUSY particles with masses below the W/Z mass, which we don't.

Furthermore, if SUSY is supposed to solve the "gauge hierarchy problem" it would seem very strange to demand EWSB happens at a HIGHER scale than SUSY breaking. Part of the beauty of the MSSM is that EWSB occurs for free!

As to your statement about N=1 vs N=2: the massive N=1 multiplet is the same as the massless N=2 multiplet. Keep reading Terning.

Finally about the Dirac gaugino: I'm confused what you are asking. You want there to be two (Weyl) fermions to make a massive gaugino. These are like the electron and positron that make the Dirac Electron. There is no problem with charges - one of the Weyl spinors makes a particle and the other makes the antiparticle, as CPT requires. nrqed and I had a running thread on this a while back.

 

[arivero]

But if the two Weyl spinors are in the same supermultiplet, is it possible to put them in the same Dirac particle? I guess not.

I suposse that the scheme in the SMM is that the two spinors in the W+ supermultiplet build two dirac spinors joining with the two spinors in the W- supermultiplet. On other hand, the two spinors in the Z0 supermultiplet should combine between themselves, and I am a bit puzzled about it.

 

[blechman]

Why is it a problem that particles of equal and opposite charges are in the same multiplet? The electron and the positron are in the same Lorentz multiplet (the Dirac spinor) that that doesn't seem to be a problem! As SUSY is a spacetime symmetry, the analogy is more or less exact. It's not a problem.

A massive vector multiplet can be thought of as a massless vector + chiral multiplet. One spinor is the spinor in the vector multiplet, and the other is the spinor in the chiral multiplet. Then these two spinors have opposite charges, as they must have to avoid anomalies.

Ws and Zs are a little more complicated because there is the added complication of electroweak symmetry breaking. This is why we never talk about "zinos" and "photinos". Rather, you should say that the neutral wino and the "bino" (weak hypercharge gaugino) have partners.

In this (weak isospin) basis, we also do not talk about W+ or W-, but W1 and W2. It is THESE gauginos that get doubled, and then various combinations of them become charged after electroweak symmetry is broken to electromagnetism.

 

[arivero]

In this (weak isospin) basis, we also do not talk about W+ or W-, but W1 and W2. It is THESE gauginos that get doubled, and then various combinations of them become charged after electroweak symmetry is broken to electromagnetism.

OK, I was not putting attention to this point. It is very important to me to understand all this mixing of charges.

Particularly, what I am guessing is that if a fermion is not Dirac, it can not see the electric charge. And, that still it should see the chiral interactions.