The Z(4430) and a New Paradigm for Spin Interactions in Tetraquarks

Following the recent confirmation of the Z+(4430) resonance with J^{PG}=1^{++}, we have re-examined the model of S- and P-wave tetraquarks. We propose a `type-II’ diquark-antidiquark model which shows to be very effective at producing a simple and comprehensive picture of the J^{PG}=1^{++} and 1^{–} sectors of the recently discovered charged tetraquarks and of the observed Y resonances. The model is still faced with the unresolved difficulty of explaining why some states seem to have incomplete isospin multiplets.