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

TL;DR

This paper reports the observation of a narrow resonance near 1870 MeV in neutrino-induced reactions, potentially indicating an exotic isospin-3/2 baryon state decaying into a Lambda, kaon, and pion.

Contribution

First experimental search for isospin-3/2 $ ext{Xi}$ states via neutrino interactions, identifying a possible new exotic baryon resonance.

Findings

Observed a narrow peak at 1870 MeV in invariant-mass spectrum.

Resonance width consistent with detector resolution, suggesting a genuine state.

Potential identification as an exotic baryon with isospin 3/2 and strangeness -2.

Abstract

A narrow peak near 1870 MeV is observed in the combined invariant-mass spectrum of the systems $\Lambda K^0_S \pi^-$, $\Lambda K^0_S \pi^+$, $\Lambda K^- \pi^-$, and $\Lambda K^- \pi^+$ formed in $\nu_\mu$- and $\bar{\nu_\mu}$-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 $S = -2$.