Using π2(1670)→b1(1235)π to constrain hadronic models

We show that current analyses of experimental data indicate that the strong decay mode π2→b1π is anomalously small. Non-relativistic quark models with spin-1 quark pair creation, such as 3P0, 3S1 and 3D1 models, as well as instanton and lowest order one-boson (in this case π) emission models, can accommodate the analyses of experimental data, because of a quark-spin selection rule. Models and effects that violate this selection rule, such as higher order one-boson emission models, as well as mixing with other Fock states, may be constrained by the small π2→b1π decay. This can provide a viability check on newly proposed decay mechanisms. We show that for mesons made up of a heavy quark and anti-quark, the selection rule is exact to all orders of quantum chromodynamics (QCD) perturbation theory.