Observation of an Excited Charm Baryon Ω∗c Decaying to Ω0cγ

Abstract

We report the first observation of an excited singly charmed baryon Ω ∗ c ( c s s ) in the radiative decay Ω 0 c γ , where the Ω 0 c baryon is reconstructed in the decays to the final states Ω − π + , Ω − π + π 0 , Ω − π + π − π + , and Ξ − K − π + π + . This analysis is performed using a data set of 230.7 fb − 1 collected by the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. The mass difference between the Ω ∗ c and the Ω 0 c baryons is measured to be 70.8 ± 1.0 ( stat ) ± 1.1 ( syst ) MeV / c 2 . We also measure the ratio of inclusive production cross sections of Ω ∗ c and Ω 0 c in e + e − annihilation.