Unified Fano-like interference picture for charmonium-like states $Y(4008)$, $Y(4260)$ and $Y(4360)$

TL;DR

This paper introduces a unified Fano-like interference model to explain the asymmetric line shapes of charmonium-like states $Y(4008)$, $Y(4260)$, and $Y(4360)$ in electron-positron annihilation, suggesting they are not genuine resonances.

Contribution

The study applies Fano-like interference to interpret charmonium-like states, providing a novel explanation for their observed line shapes and absence in certain decay channels.

Findings

Y(4008), Y(4260), and Y(4360) are not true resonances.

Fano interference explains asymmetric line shapes.

Predictions for Fano phenomena in other processes.

Abstract

We propose that the unified Fano-like interference picture applies to $e^+e^-\to \pi^+\pi^- J/\psi$ and $e^+e^-\to \pi^+\pi^- \psi(3686)$, where $Y(4260)$ and $Y(4360)$ are observed, respectively, to provide a reasonable interpretation of the asymmetric lines hapes of $Y(4260)$ and $Y(4360)$ structures. Moreover, the Fano-like interference induces an extra broad structure $Y(4008)$ in $e^+e^-\to \pi^+\pi^- J/\psi$ as a companion peak to $Y(4260)$. Three charmonium-like states $Y(4008)$, $Y(4260)$ and $Y(4360)$ observed in $e^+e^-$ annihilation processes are not genuine resonances. Under this scenario, it is well explained why $Y(4008)$, $Y(4260)$ and $Y(4360)$ are absent in the experimental data of the $R$ value scan and missing in open-charm decay channels. Although the present work presents a typical application of the Fano-like interference in particle physics at the lower energy region, we have reason to believe that the Fano-like phenomena may exist in other processes such as $e^+e^-\to \pi^+\pi^-\psi(3770)$ and $e^+e^-\to K^+K^- J/\psi$, which will be accessible at BESIII and forthcoming BelleII.