The q-deformed quark model: quantum isospin and q-hadrons

We consider the possibility that the SU(2) isospin symmetry, exact in strong interactions but only approximate in nature, is in fact a quantum group. Using a doublet of q-quarks, we build the wavefuntions of pi-mesons, nucleons and Delta baryons. We redo the usual quark model computation for the magnetic moments and mass relations, and everything fits with experimental data. We find, nevertheless, that it is impossible to parametrize successfully the large mass difference between the charged and neutral pions with the single q of the quantum group U_q(sl(2)).