title: Diquarks and exotic spectroscopy.
abstract: 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;(f) plus sign in circle 8(f). The Roper resonance and the P11(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.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Jaffe
authors.forename: Frank
authors.initials: F
authors.lastname: Wilczek