Hadron Spectroscopy: Eberhard Klempt & Diquarks

[arivero]

Any recommendation? I have found this one very spectacular:

hep-ph/0404270
Eberhard Klempt
Glueballs, Hybrids, Pentaquarks : Introduction to Hadron Spectroscopy and Review of Selected Topics

Myself I am having some interest on diquarks but from a peculiar point of view about family symmetry. Usually scalar diquarks are pictured as antisymmetric both in spin and flavour. But if you separate flavour into isospin plus family the situation is more complicated, and becomes worse if you want consider weak isospin, which is chiral. My hope/conjecture for the outcome is that Q=4/3 scalar diquarks are still forbidden, but Q=2/3 become allowed. The current view only allows for Q=2/3 scalar diquarks when families are mixed, for instance (ds), but not (dd).

 

[Meir Achuz]

Myself I am having some interest on diquarks but from a peculiar point of view about family symmetry. Usually scalar diquarks are pictured as antisymmetric both in spin and flavour. But if you separate flavour into isospin plus family the situation is more complicated, and becomes worse if you want consider weak isospin, which is chiral. My hope/conjecture for the outcome is that Q=4/3 scalar diquarks are still forbidden, but Q=2/3 become allowed. The current view only allows for Q=2/3 scalar diquarks when families are mixed, for instance (ds), but not (dd).

I don't have time to read Klemt, but will address your question.
Just as (ds) is an allowed scalar diquark, so is (cu) with Q=4/3.
I can understand your hope, but it does not seem like a reasonable conjecture.

 

[arivero]

Just as (ds) is an allowed scalar diquark, so is (cu) with Q=4/3.
I can understand your hope, but it does not seem like a reasonable conjecture.

Well the first idea was to separate flavour in a family times a (weak?) isospin symmetry. For the sake of discussion, asume weak isospin is vectorial. Symmetrisation of spin times isospin should now disallow both ds and cu. But we know that the Up quarks have a symmetry structure different from the down family: the top is very masive. So it could be that considering the triple product of spin times isospin times family the scalar uu, uc, cc where still forbidden but the scalars dd ds ss etc were allowed.

this is we have the UU diquarks should be spin antisymmetric, isospin antisymmetric and family symmetric, while the DD diquarks should be spin antisymmetric, isospin symmetric and family antisymmetric.

If the family trick can not work, I could then think about an extra quantum number for the down quarks. What I want, in any case, is to rule out exclusively the Q=4/3 diquarks.

The idea comes from that previous observation I did last year, that in this case we get at the end six scalars for each charge and we can carry them in N=1 susymultiplets with the previous quarks, as these sets would coincide both in electric charge, colour charge, and degrees of freedom.