QCD Coulomb Gauge Approach to Exotic Hadrons
  The Coulomb gauge Hamiltonian model is used to calculate masses for selected J^{PC} states consisting of exotic combinations of quarks and gluons: ggg glueballs (oddballs), q bar{q} g hybrid mesons and q bar{q} q bar{q} tetraquark systems. An odderon Regge trajectory is computed for the J^{--} glueballs with intercept much smaller than the pomeron, explaining its nonobservation. The lowest 1^{-+} hybrid meson mass is found to be just above 2.2 GeV while the lightest tetraquark state mass with these exotic quantum numbers is predicted around 1.4 GeV consistent with the observed pi(1400). 
Stephen R. Cotanch, Ignacio J. General and Ping Wang