Study of $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0}$ at $\sqrt{s}$ from 2.00 to 3.08 GeV at BESIII

TL;DR

This study measures the cross sections of the process e+e- to three pions at energies 2.00-3.08 GeV, performs a partial wave analysis, and observes a new structure possibly indicating an excited omega state.

Contribution

It provides precise measurements of the cross sections and identifies a new resonance structure, improving previous uncertainties by a factor of ten.

Findings

Measured cross sections consistent with previous results within uncertainties.

Observed a resonance at 2119 MeV/c^2 with 5.9 sigma significance.

Identified a structure likely representing an excited omega state.

Abstract

With the data samples taken at center-of-mass energies from 2.00 to 3.08 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis on the $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0}$ process is performed. The Born cross sections for $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0}$ and its intermediate processes $e^{+}e^{-}\rightarrow\rho\pi$ and $\rho(1450)\pi$ are measured as functions of $\sqrt{s}$. The results for $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0}$ are consistent with previous results measured with the initial state radiation method within one standard deviation, and improve the uncertainty by a factor of ten. By fitting the line shapes of the Born cross sections for the $e^{+}e^{-}\rightarrow\rho\pi$ and $\rho(1450)\pi$, a structure with mass $M = 2119\pm11\pm15\ {\rm MeV}/c^2$ and width $\Gamma=69\pm30\pm5 {\rm MeV}$ is observed with a significance of $5.9\sigma$, where the first uncertainties are statistical and the second ones are systematic. This structure can be intepreteted as an excited $\omega$ state.