Puzzles in hadronic transitions of heavy quarkonium with two pion emission

TL;DR

This paper investigates anomalously large hadronic transition rates in heavy quarkonia, using a constituent quark model and QCD multipole expansion, explaining some anomalies via hybrid states and molecular components.

Contribution

It introduces a parameter-free extension of the constituent quark model to calculate hybrid states, providing new insights into hadronic transition anomalies in heavy quarkonia.

Findings

Hybrid states near resonance masses explain some anomalies.

Molecular components in wave functions justify other anomalies.

Certain unexpected results are identified.

Abstract

We study the anomalously large rates of some hadronic transitions observed in heavy quarkonia using a constituent quark model which has been successful in describing meson and baryon phenomenology. QCD multipole expansion (QCDME) is used to described the hadronic transitions. The hybrid intermediate states needed in the QCDME method are calculated in a natural, parameter-free extension of our constituent quark model based on the Quark Confining String (QCS) scheme. Some of the anomalies are explained due to the presence of a hybrid state with a mass near the one of the decaying resonance whereas others are justified by the presence of molecular components in the wave function. Certain unexpected results are pointed out.