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

TL;DR

This paper reports the first observation of a charmless purely baryonic decay of the Lambda_b^0 baryon, using LHCb data, measuring its branching fraction with a significance of 5.1 sigma.

Contribution

It presents the first experimental observation and measurement of the decay Lambda_b^0 → Lambda p p̄, expanding understanding of baryonic decay processes.

Findings

First observation of the decay with 5.1 sigma significance.

Measured relative branching fraction of approximately 5.13%.

Used full Run 2 LHCb dataset with 6.0 fb^{-1} luminosity.

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 $6.0~fb^{-1}$. 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 $\left(5.13 \pm 1.28_{\rm stat} \pm 0.27_{\rm syst}\right)\times 10^{-2}$ in the region $m(h^+h^-)< 2.85$ GeV.