# Rare $\Lambda_b\to n l^+l^-$ decays in the relativistic quark-diquark picture

## TL;DR

This paper calculates form factors and decay observables for rare Lambda_b to neutron decays using a relativistic quark-diquark model, providing predictions for branching fractions and asymmetries relevant for LHC measurements.

## Contribution

It introduces a relativistic quark-diquark approach to compute form factors for Lambda_b decays, including relativistic effects and full kinematic dependence, offering new theoretical predictions.

## Key findings

- Branching fraction for Lambda_b to n mu+ mu- is approximately 3.75 x 10^-8.
- Predicted decay observables can be measured at the LHC.
- The model provides explicit momentum transfer dependence of form factors.

## Abstract

The form factors of the rare $\Lambda_b\to n l^+l^-$ decays are calculated in the framework of the relativistic quark-diquark picture of baryons with the consistent account of the relativistic effects. Their momentum transfer squared dependence is determined explicitly in the whole accessible kinematical range. The decay branching fractions, forward-backward asymmetries and the fractions of longitudinally polarized dileptons are determined. The branching fraction of the rare $\Lambda_b\to n\mu^+\mu^-$ decay are found to be ${\rm Br}(\Lambda_b\to n\mu^+\mu^-)=(3.75\pm0.38)\times10^{-8}$ and thus could be measured at the LHC. Prediction for the branching fraction of the rare radiative $\Lambda_b\to n \gamma$ decay is also given.