3 years ago

# Study of the Dalitz decay $J/ψ→{e}^{+}{e}^{−}η$

We study the electromagnetic Dalitz decay $J/ψ→{e}^{+}{e}^{−}η$ and search for dielectron decays of a dark gauge boson (${γ}^{′}$) in $J/ψ→{γ}^{′}η$ with the two $η$ decay modes $η→γγ$ and $η→{π}^{+}{π}^{−}{π}^{0}$ using $(1310.6±7.0)×{10}^{6}\text{ }\text{ }J/ψ$ events collected with the BESIII det...