Measurement of $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}D^{+}D^{-}$ cross sections at center-of-mass energies from 4.190 to 4.946 GeV

TL;DR

This study measures the cross sections of the process e+e- to pi+ pi- D+ D- across energies from 4.190 to 4.946 GeV, revealing two resonance structures and evidence for a new vector state around 4706 MeV/c^2.

Contribution

First measurement of e+e- to pi+ pi- D+ D- cross sections over this energy range, identifying two resonance structures and providing evidence for a new vector state at 4706 MeV/c^2.

Findings

Observation of a resonance at 4373 MeV/c^2 consistent with Y(4390)

Evidence for a new vector state at 4706 MeV/c^2 with 4.1 sigma significance

Evidence for X(3842) in the D+ D- final state with 4.2 sigma significance

Abstract

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, we measure the cross sections of the $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}D^{+}D^{-}$ process at center-of-mass energies from 4.190 to 4.946 GeV with a partial reconstruction method. Two resonance structures are seen and the resonance parameters are determined from a fit to the cross section line shape. The first resonance we observe has a mass of (4373.1 $\pm$ 4.0 $\pm$ 2.2) MeV/$c^2$ and a width of (146.5 $\pm$ 7.4 $\pm$ 1.3) MeV, in agreement with those of the $Y(4390)$ state; the other resonance has a mass of (4706 $\pm$ 11 $\pm$ 4) MeV/$c^2$, a width of (45 $\pm$ 28 $\pm$ 9) MeV, and a statistical significance of $4.1$ standard deviations ($\sigma$). This is the first evidence for a vector state at this mass value. The spin-$3$ $D$-wave charmonium state $X(3842)$ is searched for through the $e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}X(3842)\rightarrow\pi^{+}\pi^{-}D^{+}D^{-}$ process, and evidence with a significance of $4.2\sigma$ is found in the data samples with center-of-mass energies from 4.600 to 4.700 GeV.