^{1}

^{1}

^{1}

^{3}.

Many vector charmonium-like states have been reported recently in the cross sections of

In the last decade, charmonium physics has gained renewed strong interest from both the theoretical and the experimental side, due to the observation of a series of charmonium-like states, such as the

Recently, with higher statistic data, the

The parameters for

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These states challenge the understanding of charmonium spectroscopy as well as QCD calculations [

Figure

Cross sections of

These vector charmonium-like states in the fit are assumed to be resonances. We parameterize the cross section with the coherent sum of a few amplitudes, either resonance represented by a Breit-Wigner (BW) function or nonresonant production term parameterized with a phase space function or an exponential function. The BW function used in this article is [

Ref. [

We fit to the cross sections of

Figure

The fitted parameters from the combined fit to the cross sections of

Parameter | | | |
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Parameter | SolutionI | SolutionII | SolutionIII | SolutionIV |
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The results of the combined fit to the cross sections of

From the fit results, the obtained parameters of

The systematic uncertainties on the resonant parameters in the combined fit to the cross sections of

Since the uncertainty of the beam energy is about 0.8 MeV at BESIII, so the uncertainty of the resonant parameters caused by the beam energy is estimated by varying

The leptonic decay width for a vector state is an important quantity for discriminating various theoretical models [

and

By inserting the numbers from Table

and

On the other hand, if we take the results with the largest

In summary, a combined fit is performed to the cross sections of

All the data used in this work are from Ref. [

The authors declare that they have no conflicts of interest.

This work is supported by the Foundation of Henan Educational Committee (No. 19A140015), Nanhu Scholars Program for Young Scholars of Xinyang Normal University, and Open Research Program of Large Research Infrastructures (2017), Chinese Academy of Sciences.

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