The anomalous suppression of π2(1670) → b1(1235) π

Abstract

We show that current experimental data indicate that the strong decay mode π 2 → b 1 π is anomalously small (more than 3 times smaller than all other decay modes of the π 2. This acts as a powerful discriminator for and against various decay models. Non-relativistic quark models with spin-1 pair creation, e.g. 3 P 0 (flux-tube breaking) and 3 S 1 and 3 D 1 (chromo-electric string-breaking) models, as well as lowest order one-boson (in this case π) emission models, can accommodate the experimental data because of a quark-spin selection rule. Models that violate the selection rule, e.g. higher order one-boson emisson decay mechanisms, as well as mixing with other Fock states and relativistic effects, may be constrained by the small π 2 → b 1 π decay.