Evidence for formation of a narrow Kosp resonance with mass near 1533 MeV in neutrino interactions

A narrow baryon resonance is observed in the invariant mass of the (KSP)-P-0 system formed in S neutrino and antineutrino collisions with nuclei. The mass of the resonance is estimated at 1533 +/- 5 MeV The observed width is less than 20 MeV and is compatible with being entirely due to experimental resolution. The statistical significance of the signal is near 6.7 standard deviations. Since the position of the observed resonance does not match the mass of any known Sigma(*+) states, we believe that it arises from the neutrino production of the Theta(+) pentaquark baryon. The analysis is based on the data obtained in past neutrino experiments with big bubble chambers: WA21, WA25, WA59, E180, and E632. (C) 2004 MAIK Nauka/Interperiodica.