Invariant-Mass Distributions from Inelasticνandν¯Interactions

The measured distributions in invariant mass $W$ of the recoiling hadron systems in neutrino- and antineutrino-nucleon inelastic collisions are observed to be significantly different after taking into account the opposite helicities of neutrinos and antineutrinos. These distributions indicate the onset of a new phenomenon in the antineutrino data beginning at an incident energy of about 30 GeV, which appears as an excess of events with $W>\mathrm{}4\mathrm{}$ GeV/${\mathit{c}}^2$.