Hybrid phenomenology in a chiral approach

Abstract

We calculate masses and decays of the (lightest) hybrid nonet with exotic quantum numbers JPC= 1 - + and the nonet of their chiral partners with JPC= 1 + - in the framework of the extended Linear Sigma Model (eLSM). As an input, we identify π1hyb=π1(1600) as a low-lying hybrid. We investigated interaction terms which fulfill chiral symmetry. For what concerns π1hyb, the most important decays are π1hyb→b1π, π1(1600) → ρπη, π1hyb→ρπ, and π1hyb→KK∗(892). The decays π1hyb→ηπ and π1hyb→η′π are expected to be small but nonzero: they follow from a chirally symmetric interaction term that breaks explicitly the axial anomaly. For all the other members of the two hybrid nonets (for which no experimental candidates exist yet), we report decay ratios that may guide ongoing and future experiments.