Evidence forΔS=−ΔQCurrents or Charmed-Baryon Production by Neutrinos

Abstract

We report on the production by neutrinos of an event with negative strangeness. In an exposure of the Brookhaven National Laboratory 7-ft cryogenic bubble chamber to a broad-band neutrino beam 335 events were observed, one of which fits the reaction $\nu p\to {\mu }^{-}{\Lambda }^0{\pi }^{+}{\pi }^{+}{\pi }^{+}{\pi }^{-}$. Alternative explanations are examined and none found with a probability greater than 3 × ${10}^{-5\mathrm{}}$. The event thus represents a large violation of the $\Delta S=\Delta Q$ rule or alternatively the production and decay of a charmed baryon state. The most plausible mass for this state is found to be 2426 ± 12 MeV.