Search for the $\Lambda_b \rightarrow \Lambda \eta^\prime$ and $\Lambda_b \rightarrow \Lambda \eta$ decays with the LHCb detector

TL;DR

This paper reports a search for specific baryonic decays of the Lambda_b particle using LHCb data, setting upper limits on one decay mode and finding evidence for another at 3 sigma significance.

Contribution

It provides the first search results for Lambda_b to Lambda eta' and eta decays, establishing upper limits and evidence levels with experimental data.

Findings

No significant signal for Lambda_b to Lambda eta' decay.

Evidence for Lambda_b to Lambda eta decay at 3 sigma significance.

Upper limit on Lambda_b to Lambda eta' branching fraction: <3.1×10^{-6}.

Abstract

A search is performed for the as yet unobserved baryonic $\Lambda_b \rightarrow \Lambda \eta^\prime$ and $\Lambda_b \rightarrow \Lambda \eta$ decays with 3$fb^{-1}$ of proton-proton collision data recorded by the LHCb experiment. The $B^0 \rightarrow K_S^0 \eta^\prime$ decay is used as a normalisation channel. No significant signal is observed for the $\Lambda_b \rightarrow \Lambda \eta^\prime$ decay. An upper limit is found on the branching fraction of $\mathcal{B}(\Lambda_b \rightarrow \Lambda \eta^\prime)<3.1\times10^{-6}$} at 90\% confidence level. Evidence is seen for the presence of the $\Lambda_b \rightarrow \Lambda \eta$ decay at the level of $3\sigma$ significance, with a branching fraction $\mathcal{B}(\Lambda_b \rightarrow \Lambda \eta)=(9.3^{+7.3}_{-5.3})\times10^{-6}$}.