Observation of $B^{+}\to p\overline{p}{\pi }^{+}$, $B^0\to p\overline{p}{K}^0$, and $B^{+}\to p\overline{p}{K}^{*+}$

We report the first observation of a $b\to u$ type charmless baryonic $B$ decay, $B^{+}\to p\overline{p}{\pi }^{+}$, as well as $b\to s$ type $B^0\to p\overline{p}{K}^0$ and $B^{+}\to p\overline{p}{K}^{*+}$ decays. The analysis is based on a $78{\mathrm{fb}}^{-1}$ data sample recorded on the ${\rm Y}(4S)$ resonance with the Belle detector at KEKB. We find $\mathcal{B}(B^{+}\to p\overline{p}{\pi }^{+})=({3.06}_{-0.62}^{+0.73}\pm 0.37)\times {10}^{-6}$, $\mathcal{B}(B^0\to p\overline{p}{K}^0)=({1.88}_{-0.60}^{+0.77}\pm 0.23)\times {10}^{-6}$, and $\mathcal{B}(B^{+}\to p\overline{p}{K}^{*+})=({10.3}_{-2.8-1.7}^{+3.6+1.3})\times {10}^{-6}$. We also update $\mathcal{B}(B^{+}\to p\overline{p}{K}^{+})=({5.66}_{-0.57}^{+0.67}\pm 0.62)\times {10}^{-6}$ and present an upper limit on $\mathcal{B}(B^0\to p\overline{p}{K}^{*0})$ at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.