Search for the rare decay $J\mathrm{/}\psi \to \gamma D^0+c\mathrm{.}c\mathrm{.}$ at BESIII

Using $(10087\pm 44)\times {10}^{6}J\mathrm{/}\psi$ events collected with the BESIII detector, we search for the rare decay $J\mathrm{/}\psi \to \gamma D^0+c\mathrm{.}c\mathrm{.}$ for the first time. No obvious signal is observed and the upper limit on the branching fraction is determined to be $\mathcal{B}(J\mathrm{/}\psi \to \gamma D^0+c\mathrm{.}c\mathrm{.})<9.1\times {10}^{-8}$ at 90% confidence level.