Observation of the charmless purely baryonic decay ${\Lambda }_b^0\to \Lambda p\bar{p}$ at LHCb

Abstract

The first observation of a charmless purely baryonic decay, ${\Lambda }_b^0\to \Lambda p\bar{p}$, is reported using the full Run 2 LHCb dataset, corresponding to an integrated luminosity of $6.0f{b}^{-1}$. The branching fraction is measured relative to that of the topologically similar normalisation mode ${\Lambda }_b^0\to \Lambda K^{+}{K}^{-}$. A simultaneous fit to the long- and downstream-track categories yields a signal significance of $5.1\sigma$ after including systematic uncertainties. The relative branching fraction is measured to be $\left(5.13\pm 1.28_{\mathrm{stat}}\pm 0.27_{\mathrm{syst}}\right)\times 10^{-2}$ in the region $m(h^{+}{h}^{-})<2.85$ GeV.

Contribution to the 2026 Electroweak session of the 60th Rencontres de Moriond