Measurement of the branching ratio and form factor for ${\mathit{K}}_{\mathit{L}}$→${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{-}}$γ

We report on measurements of the ${\mathit{K}}_{\mathit{L}}$ Dalitz decay ${\mathit{K}}_{\mathit{L}}$→${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$γ. The results are based on a sample of 919 events. Through an evaluation of the form factor, we have established evidence for a nonvanishing contribution due to the ${\mathit{KK}}^{\mathrm{*}}$γ coupling. We have determined the branching ratio to be B(${\mathit{K}}_{\mathit{L}}$→${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$γ)=(9.1±0.$4_{\mathrm{-}0.5}^{+0.6\mathrm{}}$)×${10}^{\mathrm{-}6}$.