Observation of Three Resonant Structures in the Cross Section of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$

Abstract

Using $e^{+}{e}^{-}$ collision data collected with the BESIII detector operating at the Beijing Electron Positron Collider, the cross section of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$ is measured at 59 points with center-of-mass energy $\sqrt{s}$ ranging from $4.009$ to $4.950\mathrm{GeV}$ with a total integrated luminosity of $22.2{\mathrm{fb}}^{-1}$. The cross section between $4.3$ and $4.45\mathrm{GeV}$ exhibits a plateau-like shape and drops sharply around $4.5\mathrm{GeV}$, which cannot be described by two resonances only. Three coherent Breit-Wigner functions are used to parameterize the $\sqrt{s}$-dependent cross section line shape. The masses and widths are determined to be $M_1=(4223.6_{-3.7-2.9}^{+3.6+2.6})\mathrm{MeV}/c^2$, ${\Gamma }_1=(58.5_{-11.4-6.5}^{+10.8+6.7})\mathrm{MeV}$, $M_2=(4327.4_{-18.8-9.3}^{+20.1+10.7})\mathrm{MeV}/c^2$, ${\Gamma }_2=(244.1_{-27.1-18.3}^{+34.0+24.2})\mathrm{MeV}$, and $M_3=(4467.4_{-5.4-2.7}^{+7.2+3.2})\mathrm{MeV}/c^2$, ${\Gamma }_3=(62.8_{-14.4-7.0}^{+19.2+9.9})\mathrm{MeV}$. The first uncertainties are statistical and the second are systematic. The inclusion of the relatively narrower third component proves crucial for reproducing the drop at around 4.5~GeV. The statistical significance of the three-resonance assumption over the two-resonance assumption is greater than $5\sigma$.

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Cited by in corpus (2)

• Prospects for observing the missing $2D$ and $1F$ charmonium states around 4 GeV
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