Four-quark hadrons: An updated review

Esposito, Angelo; Guerrieri, Andrea L.; Piccinini, F.; Pilloni, A.; Polosa, A. D.

doi:10.1142/s0217751x15300021

Cited by 273 publications

(267 citation statements)

References 398 publications

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“…According to PDG [1], the Z(3930) is the χ c2 (2P) charmonium state and the X(3915) is the χ c0 (2P) charmonium state. The hyperfine splitting between the Z(3930) and X(3915) is only 6% of that between the χ c2 (1P) and χ c0 (1P) [57], which is unexpectedly smaller than the potential model prediction [813]. Such a splitting was also much smaller than the corresponding splitting of m χ b2 −m χ b0 [1].…”

Section: Y(4630)mentioning

confidence: 76%

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The hidden-charm pentaquark and tetraquark states

et al. 2016

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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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Section: Y(4630)mentioning

confidence: 76%

“…Interested readers may also consult reviews in Refs. [40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,39].…”

Section: General Status Of Hadron Spectroscopymentioning

confidence: 99%

The hidden-charm pentaquark and tetraquark states

et al. 2016

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“…Such exotic states are heavily studied in the meson sector, where a number of candidates for qqqq states have been detected in recent experiments such as Belle, BABAR, BES and LHCb, see e.g. [282,283] for recent reviews. In the baryon sector, five-quark states are of considerable interest especially since the experimental signature of a potential pentaquark has been reported at LHCb [2].…”

Section: Extracting the Hadron Spectrum From Qcdmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

421

542

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We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties explored by the coupling to external (electromagnetic and other) currents. Both present many unsolved problems despite decades of experimental and theoretical research. We discuss the progress in these fields from a theoretical perspective, focusing on nonperturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We give a systematic overview as to how results are obtained in this framework and explain technical connections to lattice QCD. We also discuss the mutual relations to the quark model, which still serves as a reference to distinguish 'expected' from 'unexpected' physics. We confront recent results on the spectrum of non-strange and strange baryons, their form factors and the issues of two-photon processes and Compton scattering determined in the DysonSchwinger framework with those of lattice QCD and the available experimental data. The general aim is to identify the underlying physical mechanisms behind the plethora of observable phenomena in terms of the underlying quark and gluon degrees of freedom.

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“…[22,23] when we give details of the coupled-channel formulation). Alternative scenarios for a non qq structure of these states have been also given [30][31][32][33][34][35]. With two channels and three energy levels one is forced to treat the three components of the coupled-channel potential (V 11 , V 12 , V 22 ) as being energy independent.…”

Section: Jhep05(2015)153mentioning

confidence: 99%

Reanalysis of lattice QCD spectra leading to the D s0 ∗ (2317) and D s1 ∗ (2460)

Torres

Oset

Prelovšek

et al. 2015

J. High Energ. Phys.

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Abstract:We perform a reanalysis of the energy levels obtained in a recent lattice QCD simulation, from where the existence of bound states of KD and KD * are induced and identified with the narrow D * s0 (2317) and D * s1 (2460) resonances. The reanalysis is done in terms of an auxiliary potential, employing a single-channel basis KD ( * ) , and a two-channel basis KD ( * ) , ηD ( * ) s . By means of an extended Lüscher method we determine poles of the continuum t-matrix, bound by about 40 MeV with respect to the KD and KD * thresholds, which we identify with the D * s0 (2317) and D * s1 (2460) resonances. Using a sum rule that reformulates Weinberg compositeness condition we can determine that the state D * s0 (2317) contains a KD component in an amount of about 70%, while the state D * s1 (2460) contains a similar amount of KD * . We argue that the present lattice simulation results do not still allow us to determine which are the missing channels in the bound state wave functions and we discuss the necessary information that can lead to answer this question.

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Four-quark hadrons: An updated review

Cited by 273 publications

References 398 publications

The hidden-charm pentaquark and tetraquark states

The hidden-charm pentaquark and tetraquark states

Baryons as relativistic three-quark bound states

Reanalysis of lattice QCD spectra leading to the D s0 ∗ (2317) and D s1 ∗ (2460)

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