# Measurement of the ratio of branching fractions of the decays $\Lambda^0_b\!\to\psi(2S) \Lambda$ and $\Lambda^0_b\!\to J/\psi \Lambda$

## TL;DR

This paper reports a precise measurement of the ratio of branching fractions between two decay modes of the Lambda_b0 baryon using LHCb data at 7 and 8 TeV, providing insights into heavy baryon decay dynamics.

## Contribution

The study presents the first precise measurement of the ratio of branching fractions for Lambda_b0 decays to psi(2S) Lambda and J/psi Lambda using LHCb data at 7 and 8 TeV.

## Key findings

- Measured ratio of branching fractions: 0.513 ± 0.023 (stat) ± 0.016 (syst) ± 0.011 (branching fractions)
- Results improve understanding of heavy baryon decay processes
- Provides data for testing theoretical models of baryon decays

## Abstract

Using $pp$ collisions corresponding to 3$\,\text{fb}^{-1}$ integrated luminosity, recorded by the LHCb experiment at centre-of-mass energies of 7 and 8$\,\text{TeV}$, the ratio of branching fractions \begin{align*} \mathcal{B}(\Lambda^0_b\!\to\psi(2S) \Lambda )/\mathcal{B}(\Lambda^0_b\!\to J/\psi \Lambda)= 0.513 \pm 0.023\, (\text{stat}) \pm 0.016 \, (\text{syst}) \pm 0.011\, (\mathcal{B}) \end{align*} is determined. The first uncertainty is statistical, the second is systematic and the third is due to the external branching fractions used.