Exotic baryons as a hadronic molecule in the heavy quark region

Yasuhiro Yamaguchi,G.E Bruno,S Spagnolo,D.M Creanza,G Chiodini,P Colangelo,E Nappi,C Corianò,F De Fazio

doi:10.1051/epjconf/201612900024

Abstract

We study the hadronic molecules formed by the coupled-channel system of D (*) Λ c and D (*) Σ c (*) , inspired by the two hidden-charm pentaquark states observed by LHCb collaborations in 2015. In these molecules, the coupled channels of D (*) Σ c (*) are important because the thresholds of these channels are approximately degenerated by the heavy quark spin symmetry. In addition, we consider the coupling to the D (*) Λ c channel whose thresholds are close to the D (*) Σ c (*) thresholds, and the coupling to the state with l ≠ 0 mixed by the tensor force. By solving the coupled-channel Schrodinger equations with the one meson exchange potentials, we study the hidden-charm hadronic molecules with I(J P ) = 1/2(3/2 ± ) and 1/2(5/2 ± ). We conclude that the J P assignment of the observed pentaquarks is 3/2 + for P + c (4380) and 5/2 − for P + c (4450), which is agreement with the results of the LHCb analysis. In addition, we give predictions for other J P = 3/2 ± states.

Highlights

In 2015, LHCb collaborations observed the two hidden-charm pentaquarks P+c (4380) and P+c (4450) in Λ0b → J/ψK− p decay [1]
We study the hadronic molecules formed by the coupled-channel system of D (∗)Λc and D (∗)Σ(c∗), inspired by the two hidden-charm pentaquark states observed by LHCb collaborations in 2015
We find that the masses increase by tens of MeV and some of states disappear when the D (∗)Λc channel or the states with large orbital angular momentum are ignored

Summary

Introduction

In 2015, LHCb collaborations observed the two hidden-charm pentaquarks P+c (4380) and P+c (4450) in Λ0b → J/ψK− p decay [1]. In the hidden-charm molecules formed by the D (∗) meson and the Σ(c∗) baryons, the D Σc, D Σ∗c, D ∗Σc and D ∗Σ∗c channels will be coupled. In the D N − D ∗N systems, the D − D ∗ mixing enhances the effect of the one pion exchange potential (OPEP) having the tensor force producing the strong attraction [30,31,32,33,34,35] We expect that this mixing is helpful to produce the attraction in the hidden-charm molecules. This full-channel coupling has never been considered so far.

Interactions

Numerical results

Summary