Evidence for formation of KS0p resonances with masses near 1532, 1578, and 1659 MeV in neutrino interactions with nuclei

Three baryon resonances with masses of 1532.2±1.3, 1577.7±1.9, and 1658.6±4.4MeV are observed in invariant mass of the KS0p system formed in neutrino and antineutrino collisions with deuterons and neon nuclei. Observed widths of the 1532-MeV and 1578-MeV resonances are consistent with being entirely due to apparatus smearing, and their intrinsic widths are restricted to Γ<12 and 23 MeV, respectively. For the 1659-MeV resonance, the data suggest a nonvanishing intrinsic width of Γ∼20MeV. Significance levels of the three signals are near 7.1σ, 5.0σ, and 4.5σ, respectively. The Σ+ hypothesis for either of these three resonances is disfavored by the data on associated Λ hyperons and on formation of the Λπ system. These resonant states are tentatively interpreted as the recently discovered pentaquark baryon Θ+(1530) and its spin/isospin partners. The analysis is based on neutrino data collected by past bubble-chamber experiments.