Coulomb gauge model for hidden charm tetraquarks

The spectrum of tetraquark states with hidden charm is studied within an effective Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the (qc̄)1(cq̄)1 singlet-singlet (molecule) and the (qc)3(q̄c̄)3 triplet-triplet (diquark), for selected JPC states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with (qq̄)1(cc̄1) states about half a GeV lighter than (qc̄)1(q̄c)1. The lightest 1 ++ and 1− − predictions are in agreement with the observed X(3872) and Y (4008) masses suggesting they are molecules with ωJ/ψ and ηhc, rather than D ∗D̄ ∗ and DD̄, type structure, respectively. Similarly, the lightest isovector 1++ molecule, having a ρJ/ψ flavor composition, has mass near the recently observed charged Zc(3900) value. These flavor configurations are consistent with observed X, Y and Zc decays to pipiJ/ψ.