Structure of pentaquarks 
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 in the chiral quark model

In the past decade many charmonium-like states were observed experimentally. Especially those charged charmoniumlike Z c states and bottomonium-like Z b states can not be accommodated within the naive quark model. These charged Z c states are good candidates of either the hidden-charm tetraquark states or molecules composed of a pair of charmed mesons. Recently, the LHCb Collaboration discovered two hidden-charm pentaquark states, which are also beyond the quark model. In this work, we review the current experimental progress and investigate various theoretical interpretations of these candidates of the multiquark states. We list the puzzles and theoretical challenges of these models when confronted with the experimental data. We also discuss possible future measurements which may distinguish the theoretical schemes on the underlying structures of the hidden-charm multiquark states.

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“…In Ref. [380], the authors performed a dynamical calculation of five-quark systems with quantum numbers I = 1 2 and…”

Section: Chiral Quark Modelmentioning

confidence: 99%

The hidden-charm pentaquark and tetraquark states

et al. 2016

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“…[7]. Here only the wave functions of each degree of freedom for the five-quark system and parts of the subclusters of three-quark and quark-antiquark are listed.…”

Section: Model and Wave Functionmentioning

confidence: 99%

“…[7]. Here we only give the expressions of the five-quark system; the wave functions for the subclusters can be found in Ref.…”

Section: Model and Wave Functionmentioning

confidence: 99%

“…For the color part, both the color singlet channels (k ¼ 1) and the hidden color channels (k ¼ 2, 3) are considered here to have an economic way to describe multiquark system [7]. For the orbital wave functions, there are four relative motions for the five-body system.…”

Section: Model and Wave Functionmentioning

confidence: 99%

“…Lots of theoretical calculations have been performed to investigate these two exotic states [7][8][9][10][11][12][13][14][15][16][17], even though the Θ þ ð1540Þ pentaquark was reported by several experimental groups [18][19][20] in 2003 and has been denied by JLab with more higher precision results [21] [LEPS Collaboration still insisted on the existence of pentaquark Θ þ ð1540Þ [22]]. Besides, it is shown that there should be notable five-quark components in the baryon resonances [23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

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Dynamical study of Ωc0 in the chiral quark model

Yang

Ping

2018

Phys. Rev. D

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Recently, the experimental results of the LHCb Collaboration suggested the existence of five new excited states of Ω 0 c : Ω c ð3000Þ 0 , Ω c ð3050Þ 0 , Ω c ð3066Þ 0 , Ω c ð3090Þ 0 , and Ω c ð3119Þ 0 ; however, the quantum numbers of these new particles are not determined now. To understand the nature of these states, a dynamical calculation of Ω 0 c both in five-quark configuration with quantum numbers IJ P ¼ 0ð 1 2 Þ − , 0ð 3 2 Þ − , 0ð 5 2 Þ − and in three-quark configuration with positive parity and negative parity was performed in the framework of the chiral quark model with the help of the Gaussian expansion method. The results show the masses both of the 1P and the 2S states in ssc systems are comparable to experimental data; Besides, ΞD, Ξ cK , and Ξ Ã cK are also possible candidates of these new particles if the parity is negative. The distances between quark pairs suggest a compact structure nature.

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The S- and P-Wave Low-Lying Baryons in the Chiral Quark Model

2018

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The 1S, 2S, 1P and 2P states of light baryons are investigated within the chiral quark model, paying particular attention to the well-known order reverse problem of 1P and 2S states. Besides a nonperturbative linearscreened confining interaction and a perturbative one-gluon exchange between quarks, we incorporate the Goldstone-boson exchanges taking into account not only the full octet of pseudoscalar mesons but also the scalar one. The scalar meson exchange potential simulates the higher order multi-pion exchange terms that appear in the chiral Lagrangian and its omission has been already admitted as a deficiency of the original model in describing, for instance, the ρ − ω splitting. The numerical approach to the three-body bound state problem is the so-called Gaußian expansion method, which is able to get a precision as good as Faddeev calculations. With a set of parameters fixed to different hadron and hadron-hadron observables, we find that the chiral potential could play an important role towards the issue on the mass order reverse problem. We extend our calculation to the qqQ and qQQ sectors (with q representing a light u-, d-, or s-quark and Q denoting the charm quark or the bottom one) in which many new states have been recently observed. Some tentative assignments are done attending to the agreement between theoretical and experimental masses; however, we admit that other sources of information are needed in order to make strong claims about the nature of these states.

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Structure of pentaquarks Pc+ in the chiral quark model

Cited by 82 publications

References 55 publications

The hidden-charm pentaquark and tetraquark states

The hidden-charm pentaquark and tetraquark states

Dynamical study of Ωc0 in the chiral quark model

The S- and P-Wave Low-Lying Baryons in the Chiral Quark Model

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