Measurement of the masses and widths of the bottom baryons Sigma_b+- and Sigma_b*+-

Abstract

Using data from proton - anti-proton collisions at the energy Ecm = 1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron, we present improved measurements of the masses and first measurements of natural widths of the four bottom baryon resonance states Sigma_b+, Sigma_b*+ and Sigma_b-, Sigma_b*-. These states are fully reconstructed in their decay modes to Lambda_b pi+-, where Lambda_b -->Lambda_c+ pi- with Lambda_c+ -->prot K- pi+. The analysis is based on a data sample corresponding to an integrated luminosity of 6.0/fb collected by an online event selection based on tracks displaced from the proton - anti-proton interaction point.