Searches for the rare hadronic decays $B^0\to p\bar{p}p\bar{p}$ and $B_s^0\to p\bar{p}p\bar{p}$

Searches for the rare hadronic decays $B^0\to p\bar{p}p\bar{p}$ and $B_s^0\to p\bar{p}p\bar{p}$ are performed using proton-proton collision data recorded by the LHCb experiment and corresponding to an integrated luminosity of 9${\mathrm{f}\mathrm{b}}^{-1}$. Significances of $9.3\sigma$ and $4.0\sigma$, including statistical and systematic uncertainties, are obtained for the $B^0\to p\bar{p}p\bar{p}$ and $B_s^0\to p\bar{p}p\bar{p}$ signals, respectively. The branching fractions are measured relative to the topologically similar normalisation decays $B^0\to J\mathrm{/}\psi (\to p\bar{p})K^{\ast 0}(\to K^{+}{\pi }^{-})$ and $B_s^0\to J\mathrm{/}\psi (\to p\bar{p})\phi (\to K^{+}{K}^{-})$. The branching fractions are measured to be $\mathcal{B}(B^0\to p\bar{p}p\bar{p})=(2.2\pm 0.4\pm 0.1\pm 0.1)\times {10}^{-8}$ and $\mathcal{B}(B_s^0\to p\bar{p}p\bar{p})=(2.3\pm 1.0\pm 0.2\pm 0.1)\times {10}^{-8}$. In these measurements, the first uncertainty is statistical, the second is systematic and the third one is due to the external branching fraction of the normalisation channel.