Observation of a Dimuon Resonance at 9.5 GeV in 400-GeV Proton-Nucleus Collisions

Abstract

Dimuon production is studied in 400-GeV proton-nucleus collisions. A strong enhancement is observed at 9.5 GeV mass in a sample of 9000 dimuon events with a mass ${m}_{{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}}>5$ GeV.