Meson and tetra-quark mixing

The mixing between qq meson and qqqq tetra-quark states is examined within an effective QCD Coulomb gauge Hamiltonian model. Mixing matrix elements of the Hamiltonian are computed and then diagonalized yielding an improved prediction for the low-lying JPC=0±+,1– isoscalar spectra. Mixing effects were found significant for the scalar hadrons but not for the 1– states, which is consistent with the ideal mixing of vector mesons. A perturbative assessment of the exact QCD kernel is also reported.