Semileptonic B−→pp¯ℓ−ν¯ℓ decays

We study the four-body exclusive semileptonic baryonic B¯ decays of B−→pp¯ℓ−ν¯ℓ (ℓ=e,μ,τ) in the standard model. We find that their decay branching ratios are about (1.0,1.0,0.5)×10−4, respectively. In particular, the electron mode is close to the corresponding CLEOʼs upper limit of 5.2×10−3, while all results are about one or two orders of magnitude larger than the previous estimated values for the inclusive modes of B¯→BB¯′ℓν¯. Clearly, both B-factories of Belle and BaBar should be able to observe these exclusive four-body modes.