Glueballs versus quarkonium - flavor symmetry signatures

Flavor symmetry selection rules provide unambiguous signatures for glueball decays at masses above 1500 MeV where many channels are open. For example, a 2++ glueball should decay into ππ, Kanti K, etaeta, eta' eta', ωω, rhorho and phiphi, but not into K*anti K nor etaeta'. A quarkonium or a four-quark state cannot go into all channels allowed for a glueball; at least one is OZI-forbidden for any choice of flavors. But any quarkonium state that goes to Kanti K should also go to K*anti K and etaeta'. These selection rules are shown to be stable against SU(3) symmetry breaking. (orig.)