The $Z_c(3900)$ peak does not come from the "triangle singularity"

Gong, Qin-Rong; Pang, Jing-Long; Wang, Yufei; Zheng, Han-Qing

doi:10.48550/arxiv.1612.08159

Cited by 9 publications

(13 citation statements)

References 12 publications

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“…They concluded that it is not possible to distinguish between these scenarios at that time, which contradicted the conclusion of Ref. [804].…”

Section: The Z C Statesmentioning

confidence: 89%

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Pentaquark and Tetraquark states

Liu,

Chen,

Chen

et al. 2019

Preprint

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The past seventeen years have witnessed tremendous progress on the experimental and theoretical explorations of the multiquark states. The hidden-charm and hidden-bottom multiquark systems were reviewed extensively in Ref. [1]. In this article, we shall update the experimental and theoretical efforts on the hidden heavy flavor multiquark systems in the past three years. Especially the LHCb collaboration not only confirmed the existence of the hidden-charm pentaquarks but also provided strong evidence of the molecular picture. Besides the well-known XY Z and P c states, we shall discuss more interesting tetraquark and pentaquark systems either with one, two, three or even four heavy quarks. Some very intriguing states include the fully heavy exotic tetraquark states QQ Q Q and doubly heavy tetraquark states QQq q, where Q is a heavy quark. The QQ Q Q states may be produced at LHC while the QQq q system may be searched for at BelleII and LHCb. Moreover, we shall pay special attention to various theoretical schemes such as the chromomagnetic interaction (CMI), constituent quark model, meson exchange model, heavy quark and heavy diquark symmetry, QCD sum rules, Faddeev equation for the three body systems, Skyrme model and the chiral quark-soliton model, and the lattice QCD simulations. We shall emphasize the model-independent predictions of various models which are truly/closely related to Quantum Chromodynamics (QCD). For example, the chromomagnetic interaction arises from the gluon exchange which is fundamental and universal in QCD and responsible for the mixing and mass splitting of the conventional mesons and baryons within the same multiplet. The same CMI

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“…They concluded that it is not possible to distinguish between these scenarios at that time, which contradicted the conclusion of Ref. [804].…”

Section: The Z C Statesmentioning

confidence: 89%

“…In Ref. [804], the same group noted that the triangle singularity mechanism did not produce the observed Z c (3900) peak. Their study again favors the molecular assignment for the Z c (3900).…”

Section: The Z C Statesmentioning

confidence: 96%

Pentaquark and Tetraquark states

Liu,

Chen,

Chen

et al. 2019

Preprint

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show abstract

“…However, it is shown in Refs. [334,336] for the case of the Z c (3900) that the triangle singularity alone cannot accommodate the data available at various energies.…”

Section: Threshold Effects Without New Statesmentioning

confidence: 99%

The $XYZ$ states: experimental and theoretical status and perspectives

Brambilla,

Eidelman,

Hanhart

et al. 2019

Preprint

139

194

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The quark model was formulated in 1964 to classify mesons as bound states made of a quark-antiquark pair, and baryons as bound states made of three quarks. For a long time all known mesons and baryons could be classified within this scheme. Quantum Chromodynamics (QCD), however, in principle also allows the existence of more complex structures, generically called exotic hadrons or simply exotics. These include four-quark hadrons (tetraquarks and hadronic molecules), five-quark hadrons (pentaquarks) and states with active gluonic degrees of freedom (hybrids), and even states of pure glue (glueballs). Exotic hadrons have been systematically searched for in numerous experiments for many years. Remarkably, in the past fifteen years, many new hadrons that do not exhibit the expected properties of ordinary (not exotic) hadrons have been discovered in the quarkonium spectrum. These hadrons are collectively known as XYZ states. Some of them, like the charged states, are undoubtedly exotic. Parallel to the experimental progress, the last decades have also witnessed an enormous theoretical effort to reach a theoretical understanding of the XYZ states. Theoretical approaches include not only phenomenological extensions of the quark model to exotics, but also modern non-relativistic effective field theories and lattice QCD calculations. The present work aims at reviewing the rapid progress in the field of exotic XYZ hadrons over the past few years both in experiments and theory. It concludes with a summary on future prospects and challenges.

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“…In Refs. [1,26,37,44,67,78], it was demonstrated that the D 1 (2420) DD * triangle diagram is important for the understanding of the Z c (3900) . It can produce a resonance-like structure, which enhances the production of near-threshold resonances [11].…”

Section: B Production Amplitudesmentioning

confidence: 99%

A combined analysis of the $Z_c(3900)$ and the $Z_{cs}(3985)$ exotic states

Du,

Albaladejo,

Guo

et al. 2022

Preprint

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We have performed a combined analysis of the BESIII data for both the Z c (3900) and Z cs (3985) structures, assuming that the latter is an SU(3) flavor partner of the former one. We have improved on the previous analysis of Ref.[1] by computing the amplitude for the D 1 DD * triangle diagram considering both D and S-wave D 1 D * π couplings. We have also investigated effects from SU(3) light-flavor violations, which are found to be moderate and of the order of 20%. The successful reproduction of the BESIII spectra, in both the hiddencharm and hidden-charm strange sectors, strongly supports that the Z cs (3985) and Z c (3900) are SU(3) flavor partners placed in the same octet multiplet. The best results are obtained when an energy-dependent term in the diagonal D ( * ) D( * )(s) interaction is included, leading to resonances (poles above the thresholds) to describe these exotic states. We have also made predictions for the isovector Z * c and isodoublet Z * cs , D * D * and D * D * s molecules, with J P C = 1 +− and J P = 1 + , respectively. These states would be heavy-quark spin symmetry (HQSS) partners of the Z c and Z cs . Besides the determination of the masses and widths of the Z c (3900) and Z cs (3985), we also predict those of the Z * c and Z * cs resonances.

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The $Z_c(3900)$ peak does not come from the "triangle singularity"

Cited by 9 publications

References 12 publications

Pentaquark and Tetraquark states

Pentaquark and Tetraquark states

The $XYZ$ states: experimental and theoretical status and perspectives

A combined analysis of the $Z_c(3900)$ and the $Z_{cs}(3985)$ exotic states

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