Sequel to the psi: DESY, SLAC see intermediate states

After the first rush of discovery last fall in which the J or psi particle, with mass of 3.1 GeV was discovered, almost immediately followed by the psi prime, with mass of 3.7 GeV, there has been no new obviously related particle discovered. That is, until now, when an intermediate state, dubbed the “$Pc$ particle” was observed at the DESY electron–positron storage ring, DORIS. The particle apparently has a mass of either 3.5 or 3.3 GeV, but the experimenters cannot tell which.