Observation of High-Mass Dilepton Pairs in Hadron Collisions at 400 GeV

We report preliminary results on the production of electron-positron pairs in the mass range 2.5 to 20 GeV in 400-GeV $p$-Be interactions. 27 high-mass events are observed in the mass range 5.5-10.0 GeV corresponding to $\sigma =(1.2\mathrm{}\pm 0.5)\times {10}^{-35\mathrm{}}$ ${\mathrm{cm}}^2$ per nucleon. Clustering of 12 of these events between 5.8 and 6.2 GeV suggests that the data contain a new resonance at 6 GeV.