The existence of a light-dark-force mediator has been tested with the KLOE detector at DAΦNE. This particle, called U, is searched for using the decay chain φ → ηU, with the final state η → π+π− π0, U → e+e−. No evidence is
found in 1.5 fb−1 of data. An upper limit on the existence of the U has been set, in the mass range 50 < MU < 420 MeV. We are studying other η dominant decay channels as the 2γ and the 3π0. The combined fit will extend the upper limit on
the overall mass range
