Observation of e + e − → π 0 π 0 ψ 2(3823)

Abstract Using a data sample corresponding to an integrated luminosity of 11.3 fb −1 collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we observe the process e + e − → π 0 π 0 ψ 2(3823) for the first time with a statistical significance of 6.0 standard deviations. The ratio of average cross sections for e + e − → π 0 π 0 ψ 2(3823) and π + π − ψ 2(3823) is determined to be R = σ e + e − → π 0 π 0 ψ 2 3823 σ e + e − → π + π − ψ 2 3823 = 0.57 ± 0.14 ± 0.05 $$ \mathcal{R}=\frac{\sigma \left[{e}^{+}{e}^{-}\to {\pi}^0{\pi}^0{\psi}_2(3823)\right]}{\sigma \left[{e}^{+}{e}^{-}\to {\pi}^{+}{\pi}^{-}{\psi}_2(3823)\right]}=0.57\pm 0.14\pm 0.05 $$ , 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 ψ 2(3823) is measured to be M[ψ 2(3823)] = 3824.5 ± 2.4 ± 1.0 MeV/c 2. Due to the limited data sample, an upper limit of 18.8 MeV at 90% confidence level is set on the intrinsic width of ψ 2(3823).