Angular distributions in three-body baryonic B decays

We study the angular distributions of the baryon-antibaryon low-mass enhancements in the three-body baryonic B decays of B{yields}ppM (M=K and {pi}) in the framework of the perturbative QCD. By writing the most general forms for the transition form factors of B{yields}pp, we find that the angular distribution asymmetry in B{sup -}{yields}ppK{sup -} measured by Belle Collaboration can be explained. We give a quantitative description on the Dalitz plot asymmetry in B{sup -}{yields}ppK{sup -} shown by BABAR Collaboration and demonstrate that it is equivalent to the angular asymmetry. In addition, we present our results on B{sup 0}{yields}ppK{sub S} and B{sup -}{yields}pp{pi}{sup -} and we obtain that their angular asymmetries are -0.35{+-}0.11 and 0.45{+-}0.10, respectively, which can be tested by the ongoing experiments at the B factories.