Observation of an Excited Charm Baryon OmegaC* Decaying to OmegaC0 Gamma

TL;DR

This paper reports the first observation of an excited charm baryon OmegaC* decaying radiatively to OmegaC0 gamma, measuring its mass difference and production ratio using data from the BABAR detector.

Contribution

First observation of the excited charm baryon OmegaC* decaying to OmegaC0 gamma, with precise measurements of its mass difference and production ratio.

Findings

Mass difference between OmegaC* and OmegaC0 is 70.8 MeV/c2.

First measurement of the production cross section ratio of OmegaC* to OmegaC0.

Observation confirms the existence of the excited OmegaC* baryon.

Abstract

We report the first observation of an excited singly-charm baryon OmegaC* (css) in the radiative decay OmegaC0 Gamma, where the OmegaC0 baryon is reconstructed in the decays to the final states Omega-pi+, Omega-pi+pi0, Omega-pi+pi-pi+, and Cascade-K-pi+pi+. This analysis is performed using a dataset 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 OmegaC* and the OmegaC0 baryons is measured to be 70.8 +/- 1.0 (stat) +/- 1.1 (syst) MeV/c2. We also measure the ratio of inclusive production cross sections of OmegaC* and OmegaC0 in e+e- annihilation.