Study of B-Meson Decays to Final States with a Single Charm Baryon

Abstract

A study of B-meson decays to final states with a single charm baryon is presented based on data recorded by the BABAR detector at the Stanford Linear Accelerator Center. Although the B meson is the lightest bottom-flavored meson, it is heavy enough to decay to a baryon made of three quarks and an antibaryon made of three antiquarks. By studying the baryonic weak decays of the B meson, we can investigate baryon production mechanisms in heavy meson decays. In particular, we measure the rates of the decays B- → Λ+c$\bar{p}$π- and $\bar{B}$0 → Λ+c$\bar{p}$. Comparing these rates, we confirm an observed trend in baryonic B decays that the decay with the lower energy release, B- → Λ+c$\bar{p}$π-, is favored over $\bar{B}$0 → Λ+c$\bar{p}$. The dynamics of the baryon-antibaryon (Λ+c$\bar{p}$) system in the three-body decay also provide insight into baryon-antibaryon production mechanisms. The B- → Λ+c$\bar{p}$π- system is a laboratory for searches for excited #c baryon states; we observe the resonant decays B- → Σc(2455) 0$\bar{p}$ and B- → Σc(2800) 0$\bar{p}$. This is the first observation of the decay B- → Σc(2800) 0$\bar{p}$; however, the mass of the observed #c(2800)0 state is inconsistent with previous measurements. Finally, we examine the angular distribution of the B- → Σc(2455) 0$\bar{p}$ decays and measure the spin of the B- → Σc(2455) 0$\bar{p}$ baryon to be J = 1/2, as predicted by the quark model.