Pentaquark symmetries, selection rules and another potentially narrow state

AbstractWe identify essential differences between the pentaquark and chiral soliton models of 105 and 85 pentaquarks and conventional 83 states, which are experimentally measurable. We show how the decays of Ξ5 states in particular can test models of the pentaquarks, recommend study of the relative branching ratios of, e.g., Ξ−5→Ξ−π0:Ξ0π−, and predict that the decay amplitude Ξ5→Ξ∗π is zero at leading order in pentaquark models for any mixture of 10 and the associated 85. We also include a pedagogic discussion of wavefunctions in the pentaquark picture and show that pentaquark models have this 85 with F/D=1/3, in leading order forbidding Ξ5→ΛK. The role of Fermi–Dirac symmetry in the qqqq wavefunction and its implications for the width of pentaquarks are briefly discussed. The relative couplings g2(ΘQNKQ∗)/g2(ΘQNKQ)=3 for Q≡s,c,b. A further potentially narrow state Λ in 85 with JP=3/2+ is predicted around 1650 MeV