Cross Section Measurement of $e^+e^- \rightarrow \pi^+\pi^-\psi(3686)$ from $\sqrt{s}=4.0076$~GeV to 4.6984~GeV

TL;DR

This paper measures the cross section of the process e+e- to pi+pi- psi(3686) across a range of energies, confirming known charmonium-like states and reporting the first observation of Y(4660) at BESIII with improved precision.

Contribution

First measurement of the e+e- to pi+pi- psi(3686) cross section with high precision and the first observation of Y(4660) at BESIII.

Findings

Confirmed existence of Y(4220), Y(4390), and Y(4660) states.

Measured cross sections with improved accuracy.

First observation of Y(4660) at BESIII.

Abstract

Using data samples with a total integrated luminosity of $20.1~\rm fb^{-1}$ collected by the BESIII detector operating at the BEPCII collider, the cross section of the process $e^+e^- \rightarrow \pi^+\pi^-\psi(3686)$ is measured at center-of-mass energies between 4.0076 and 4.6984 GeV. The measured cross section is consistent with previous results, but with much improved precision. A fit to the measured energy-dependent cross section, which includes three Breit-Wigner functions and a non-resonant contribution, confirms the existence of the charmonium-like states $Y(4220)$, $Y(4390)$, and $Y(4660)$. This is the first observation of the $Y(4660)$ at the BESIII experiment.