Study of the Baryon-Antibaryon Low-Mass Enhancements in Charmless Three-body Baryonic B Decays

The angular distributions of the baryon-antibaryon low-mass enhancements seen in the charmless three-body baryonic B decays B^+ \to p pbar K^+, B^0 \to p pbar K_S^0, and B^0 \to p Lambdabar pi^- are reported. Searches for the pentaquarks Theta^+ and Theta^{++} in the relevant decay modes and possible glueball states in the p pbar systems are presented. The analysis is based on a 140 fb^{-1} data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider.