Observation of $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823)$

Abstract

Using a data sample corresponding to an integrated luminosity of 11.3 $\mathrm{f}{\mathrm{b}}^{-1}$ collected at center-of-mass energies from $4.23$ to $4.70$~GeV with the BESIII detector, we observe the process $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823)$ for the first time with a statistical significance of $6.0\sigma$. The ratio of average cross sections for $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823)$ over ${\pi }^{+}{\pi }^{-}{\psi }_2(3823)$ is determined to be $\mathcal{R}=\frac{\sigma [e^{+}{e}^{-}\to {\pi }^0{\pi }^0{\psi }_2(3823)]}{\sigma [e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_2(3823)]}=0.57\pm 0.14\pm 0.05$, which is consistent with expectations from isospin symmetry. Here and below, the first uncertainties are statistical and the second are systematic. The mass of the ${\psi }_2(3823)$ is measured to be $M[{\psi }_2(3823)]=3824.5\pm 2.4\pm 1.0$~MeV/$c^2$. Due to the limited statistics, the intrinsic width of the ${\psi }_2(3823)$ is measured as an upper limit of $18.8$~MeV at $90\%$ confidence level.

arXiv comment16 pages, 1 figure

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