Evidence of New States Decaying into $Ξ^{\prime}_{c}π$

Abstract

Using 13.7 $fb^{-1}$ of data recorded by the CLEO detector at CESR, we report evidence for two new charmed baryons: one decaying into $Ξ_c^{0 \prime}π^+$ with the subsequent decay $Ξ_c^{0 \prime} \to Ξ_c^0 γ$, and its isospin partner decaying into $Ξ_c^{+ \prime} π^-$ followed by $Ξ_c^{+\prime} \to Ξ_c^+γ$. We measure the following mass differences for the two states: $M(Ξ_c^0 γπ^+)-M(Ξ_c^0)$=318.2+-1.3+-2.9 MeV, and $M(Ξ_c^+ γπ^-)-M(Ξ_c^+)$=324.0+-1.3+-3.0 MeV. We interpret these new states as the $J^P = 1/2^- Ξ_{c1}$ particles, the charmed-strange analogs of the $Λ_{c1}^+(2593)$.