Nonresonant explanation for the Y(4260) structure observed in the $e^+e^-\to J/\psi\pi^+\pi^-$ process

TL;DR

This paper proposes a nonresonant interference model to explain the Y(4260) structure observed in $e^+e^- o J/eta ext{pi}^+ ext{pi}^-$, suggesting it is not a genuine resonance but an interference effect.

Contribution

The study introduces a nonresonant interference explanation for Y(4260), challenging the resonance interpretation and explaining its absence in open-charm decay channels.

Findings

Successfully reproduces Y(4260) line shape without a resonance

Explains lack of Y(4260) in open-charm channels

Provides a natural explanation for Y(4260) absence in $R$-value scans

Abstract

In this work, we proposed a nonresonant explanation for the Y(4260) structure observed in the $e^+e^-\to J/\psi\pi^+\pi^-$ process, i.e., Y(4260) is not a genuine resonance. Our result indicates that the Y(4260) structure can be reproduced by the interference of production amplitudes of the $e^+e^-\to J/\psi\pi^+\pi^-$ processes via direct $e^+e^-$ annihilation and through intermediate charmonia $\psi(4160)/\psi(4415)$. Besides describing Y(4260) line shape in $e^+e^-\to J/\psi\pi^+\pi^-$ well, such a nonresonant explanation for the Y(4260) structure naturally answers why there is no evidence of Y(4260) in the exclusive open-charm decay channel and $R$-value scan.