A Study Of Excited Charm Strange Baryons Withevidence For New Baryons Xi C3055 And Xi C3123 PDF Download

In this dissertation I describe a study of double-charm and charm-strange baryons based on data collected with the BABAR Detector at the Stanford Linear Accelerator Center. In this study I search for new baryons and make precise measurements of their properties and decay modes. I seek to verify and expand upon double-charm and charm-strange baryon observations made by other experiments. The BABAR Detector is used to measure subatomic particles that are produced at the PEP-II storage rings. I analyze approximately 300 million e+e- → c{bar c} events in a search for the production of double-charm baryons. I search for the double-charm baryons?{sub cc} (containing the quarks ccd) and?{sup ++}{sub cc} (ccu) in decays to?+{sub c}K−?+ and?+{sub c}K−?+?+, respectively. No statistically significant signals for their production are found, and upper limits on their production are determined. Statistically significant signals for excited charm-strange baryons are observed with my analysis of approximately 500 million e+e- → c{bar c} events. The charged charm-strange baryons?{sub c}(2970)+,?{sub c}(3055)+,?{sub c}(3123)+ are found in decays to?+{sub c}K−?+, the same decay mode used in the?+{sub cc} search. The neutral charm-strange baryon?{sub c}(3077)° is observed in decays to?+{sub c}K?−. I also search for excited charm-strange baryon decays to?+{sub c}K8,?+{sub c}K−,?+{sub c}K8?−?+, and?+{sub c}K−?−?+. No significant charm-strange baryon signals a f h these decay modes. For each excited charm-strange baryon state that I observe, I measure its mass, natural width (lifetime), and production rate. The properties of these excited charm-strange baryons and their decay modes provide constraints for phenomenological models of quark interactions through quantum chromodynamics. My discovery of the two new charm-strange baryons?{sub c}(3055)+ and?{sub c}(3123)+ influences our theoretical understanding of charm-strange baryon states.