Photoproduction of possible pentaquark states Λb0(5912) and Λb0(5920) in the γp→Λb0(*)B+ reactions

Yin Huang,Hong Qiang Zhu

doi:10.1103/physrevd.104.056027

Abstract

In this work, we report on a theoretical study of possible pentaquark states $\Lambda^0_b(5912)$ and $\Lambda^0_b(5920)$ in the $\gamma{}p\to{}\Lambda_b^{0(*)}B^+$ reactions within an effective Lagrangian approach. In addition to the contributions from the $s$-channel nucleon pole and $t$-channel $\bar{B}^{{*}-}$ exchange, the contact term contribution are also included. Our theoretical approach is based on the chiral unitary theory where the $\Lambda^0_b(5912)$ and $\Lambda^0_b(5920)$ resonances are dynamically generated. Within the coupling constants of the $\Lambda^0_b(5912)$ and $\Lambda^0_b(5920)$ to $\bar{B}p$ and $\bar{B}^{*}p$ channels obtained from chiral unitary theory, the total and differential cross sections of the $\gamma{}p\to{}\Lambda_b^{0(*)}B^+$ are evaluated. Our calculation indicates that the cross section for $\gamma{}p\to{}\Lambda_b^{0}(5912)B^{+}$ and $\gamma{}p\to{}\Lambda_b^{0}(5920)B^{+}$ reactions are of the order of 0.0164 nb and 0.00527 nb,respectively. If measured in future experiments, such as Electron-Ion Collider in China (EicC) or US(US-EIC), the predicted total cross sections and specific features of the angular distributions can be used to test the (molecular) nature of the $\Lambda^0_b(5912)$ and $\Lambda^0_b(5920)$ that they may be pentaquark states.

Highlights

Thanks to the experimental progress in the sector of heavy baryons in the past decade, many heavy baryons that cannot be ascribed to three-quark configurations have been reported [1]
Within the coupling constants of the Λ0bð5912Þ and Λ0bð5920Þ to Bp and B Ãp channels obtained from chiral unitary theory, the total and differential cross sections of the γp → Λ0bðÃÞBþ are evaluated
The mechanism including the t channel mediated by the exchange of B Ã mesons, the contact term, and the s channel where nucleon is considered as an intermediate state

Summary

INTRODUCTION

Thanks to the experimental progress in the sector of heavy baryons in the past decade, many heavy baryons that cannot be ascribed to three-quark configurations have been reported [1]. A new possible strange hidden charm pentaquark Pcsð4459Þ was observed by the LHCb Collaboration with udscccomponent in the Ξ−b → J=ψΛK− process [3]. These findings stirred an active discussion on the structure of these states. It is easy to confirm that the new Pc [Pcð4312Þ, Pcð4440Þ, and Pcð4450Þ] and Pcsð4459Þ contain at least five valence quarks according to the quark components of decay model J=ψp and J=ψΛ [2,3] They are perfect candidates of hidden-charm pentaquark states. III, the numerical result of the γp → Λ0bðÃÞBþ will be given, followed by discussions and conclusions in the last section

THEORETICAL FORMALISM

RESULTS

SUMMARY