Search for formation of isospin-3/2 $\Xi$ states by neutrinos

Abstract

A narrow peak near 1870 MeV is observed in the combined invariant-mass spectrum of the systems $\Lambda K_S^0{\pi }^{-}$, $\Lambda K_S^0{\pi }^{+}$, $\Lambda K^{-}{\pi }^{-}$, and $\Lambda K^{-}{\pi }^{+}$ formed in ${\nu }_{\mu }$- and $\overline{{\nu }_{\mu }}$-induced charged-current collisions with free protons, deuterons, and Neon nuclei. Observed width of the resonance is consistent with being entirely due to apparatus smearing. A possible interpretation of the peak is formation and three-body $\Lambda K\pi$ decay of an exotic baryon with $I=3/2$ and $S=-2$.

7 pages, 4 figures