The spectrum of charmonium in the Resonance-Spectrum Expansion

TL;DR

This paper proposes that several observed charmonium-like structures are not true resonances but are instead caused by Regge zeros in the production amplitude within the Resonance-Spectrum Expansion framework, revealing underlying c-cbar states.

Contribution

It introduces a novel interpretation of Y(4260), Y(4360), Y(4660), and Y(4635) as non-resonant effects due to Regge zeros, challenging the resonance classification.

Findings

Y(4260), Y(4360), Y(4660), and Y(4635) are non-resonant phenomena.

Charmonium c-cbar states are visible on the slopes of these structures.

Regge zeros significantly influence the observed spectrum.

Abstract

We argue that the resonance-like structures Y(4260) (arXiv:hep-ex/0506081,arXiv:0707.2541), Y(4360), Y(4660) (arXiv:0707.3699) and Y(4635) (arXiv:0807.4458), which were recently reported to have been observed in experiment, are non-resonant manifestations of the Regge zeros that appear in the production amplitude of the Resonance-Spectrum Expansion. Charmonium c-cbar states are visible on the slopes of these enhancements.