# Pentaquarks in semileptonic $\Lambda_b$ decays

## TL;DR

This paper investigates semileptonic Lambda_b decays involving hidden charm pentaquarks, predicting branching ratios and angular correlations to aid experimental understanding of these exotic states.

## Contribution

It introduces a novel analysis of Lambda_b semileptonic decays with pentaquark states and predicts decay rates and angular asymmetries relevant for ongoing experiments.

## Key findings

- Predicted branching ratios for Lambda_b to J/psi p l nu decays (~10^-6)
- Identified contributions of pentaquark states via sea quarks or intrinsic charm
- Analyzed angular correlations to distinguish decay mechanisms

## Abstract

In terms of ${\cal P}_{c1,c2}={\cal P}_c(4380,4450)^+$ as the hidden charm pentaquark states to consist of $c\bar c uud$, we study the semileptonic $\Lambda_b\to ({\cal P}_{c1,c2}\to)J/\psi p \ell^-\bar \nu_\ell$ decays. In our discussion, while the main contribution to $\Lambda_b\to K^-J/\psi p$ is from the non-perturbative process via the doubly charmful $b\to c\bar cs$ transition, we propose that the $\Lambda_b\to {\cal P}_{c1,c2}\to J/\psi p$ transitions are partly contribute to the $\Lambda_b\to K^-({\cal P}_{c1,c2}\to)J/\psi p$ decays, in which the required $c\bar c$ pair is formed by the sea quarks, intrinsic charm, or both. We predict that ${\cal B}(\Lambda_b\to J/\psi p \ell^-\bar \nu_\ell)=(2.04^{+4.82}_{-1.57},1.75^{+4.14}_{-1.35})\times 10^{-6}$ for $\ell=(e,\mu)$, which are about two orders of magnitude smaller than the observed decay of $\Lambda_b\to p\mu\bar \nu_\mu$. We also explore the angular correlations for the $J/\psi p$ and $\ell^-\bar \nu_\ell$ pairs. Our results of the decay branching ratios and angular asymmetries in $\Lambda_b\to J/\psi p \ell^-\bar \nu_\ell$, accessible to the ongoing experiments at the LHCb, can be used to improve the understanding of the hidden charm pentaquark states.