Charmless two-body baryonic Bu,d,s decays revisited

We study charmless two-body baryonic B decays using the topological amplitude approach. We extend a previous work to include all ground state octet and decuplet final states with full topological amplitudes. Relations on rates and CP asymmetries are obtained. The number of independent topological amplitudes is significantly reduced in the large m(B) asymptotic limit. With the long awaited (B) over bar (0) -> p (p) over bar data, we can finally extract information on the topological amplitudes and predict rates of all other modes. The predicted rates are in general with uncertainties of a factor of 2 by including corrections to the asymptotic relations and from subleading contributions. We point out some modes that will cascadely decay to all charged final states and have large decay rates. For example, (B) over bar (0)(s) -> Omega(-)(Omega(-)) over bar, B- -> p (Delta(++)) over bar, B- -> A (p) over bar and (B) over bar (0)(s) -> A (A) over bar decays are interesting modes to search for. We find that the (B) over bar (0) -> p (p) over bar mode is the most accessible one among octet- antioctet final states in the Delta S = 0 transition. It is not surprise that it is the first (B) over bar (q) -> B (B) over bar mode being observed. With the detection of pi(0) and/or gamma many other unsuppressed modes can be searched for. The predicted (B) over bar (0)(s) -> p (p) over bar rate is several order smaller than the present experimental result. The central value of the experimental result can be reproduced only with unnaturally scaled up subleading contributions, which will affect other modes including the (B) over bar (0) -> p (p) over bar decay. We need more data to clarify the situation. The analysis presented in this work can be systematically improved when more measurements on decay rates become available.