Pentaquarks in semileptonic ${\Lambda }_b$ decays

Abstract

In terms of ${\mathcal{P}}_{c1,c2}={\mathcal{P}}_c(4380,4450{)}^{+}$ as the hidden charm pentaquark states to consist of $c\bar{c}uud$, we study the semileptonic ${\Lambda }_b\to ({\mathcal{P}}_{c1,c2}\to )J/\psi p{\ell }^{-}{\bar{\nu }}_{\ell }$ 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 $b\to c\bar{c}s$ transition, we propose that the ${\Lambda }_b\to {\mathcal{P}}_{c1,c2}\to J/\psi p$ transitions are partly contribute to the ${\Lambda }_b\to K^{-}({\mathcal{P}}_{c1,c2}\to )J/\psi p$ decays, in which the required $c\bar{c}$ pair is formed by the sea quarks, intrinsic charm, or both. We predict that $\mathcal{B}({\Lambda }_b\to J/\psi p{\ell }^{-}{\bar{\nu }}_{\ell })=(2.04_{-1.57}^{+4.82},1.75_{-1.35}^{+4.14})\times 10^{-6}$ 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.

arXiv comment11 pages, 3 figures, accepted by Annals of Physics

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• Parton distribution functions and constraints on the intrinsic charm content of the proton using BHPS approach
• Hidden charm ${\mathcal{P}}_{cs}(4338{)}^0$ production in baryonic $B^{-}\to J/\psi \Lambda \bar{p}$ decay