Diquarks and exotic spectroscopy

We propose that the recently discovered Theta(+) baryon is a bound state of four quarks and an antiquark, containing two highly correlated ud pairs. If so, the Theta(+) has positive parity, and it lies in an near-ideally mixed SU(3)(f) (10) over bar (f)circle plus8(f). The Roper resonance and the P-11(1710) fit naturally into this classification. We predict an isospin 3/2 multiplet of Xi's (S=-2) with J(Pi)=1/2(+) around 1750 MeV. A search for manifestly exotic Xi(+) and Xi(--) in this mass range could provide a sharp test of our proposal. We predict that charm and bottom analogs of the Theta(+) may be stable against strong decays.