Evidence of New States Decaying into Xi_c^{prime} pi

Abstract

Using 13.7 fb^{-1} of data recorded by the CLEO detector at CESR, we report preliminary evidence for two new charmed baryons; one decaying into Xi_c^{0\prime} pi^+ with the subsequent decay Xi_c^{0\prime} to Xi_c^0 gamma, and its isospin partner decaying into Xi_c^{+\prime} pi^- followed by Xi_c^{+\prime} to Xi_c^+ gamma. We measure the following mass differences for the two states: M(Xi_c^0 gamma pi^+)-M(Ξ_c^0)=318.4+-1.5+-2.9 MeV, and M(Xi_c^+ gamma pi^-)-M(Xi_c^+)=323.9+-pm1.4+-pm3.0 MeV. We interpret these new states as the J^P = (1/2)^-1 Xi_{c1} particles, the charmed-strange analogues of the Lambda_{c1}^+(2593).