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 $\ensuremath{\sigma}=(1.2\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}35}$ ${\mathrm{cm}}^{2}$ 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.