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Richard, J. M., Valcarce, A., & Vijande, J. (2017). Stable heavy pentaquarks in constituent models. Phys. Lett. B, 774, 710–714.
Abstract: It is shown that standard constituent quark models produce ((c)over-barcqqq) hidden-charm pentaquarks, where c denotes the charmed quark and q a light quark, which lie below the lowest threshold for spontaneous dissociation and thus are stable in the limit where the internal (c)over-barc annihilation is neglected. The binding is a cooperative effect of the chromoelectric and chromomagnetic components of the interaction, and it disappears in the static limit with a pure chromoelectric potential. Their wave function contains color sextet and color octet configurations for the subsystems and can hardly be reduced to a molecular state made of two interacting hadrons. These pentaquark states could be searched for in the experiments having discovered or confirmed the hidden-charm meson and baryon resonances.
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Valcarce, A., Garcilazo, H., & Vijande, J. (2014). Heavy baryon spectroscopy with relativistic kinematics. Phys. Lett. B, 733, 288–295.
Abstract: We present a comparative Faddeev study of heavy baryon spectroscopy with nonrelativistic and relativistic kinematics. We show results for different standard hyperfine interactions with both kinematics in an attempt to learn about the light quark dynamics. We highlight the properties of particular states accessible in nowadays laboratories that would help in discriminating between different dynamical models. The advance in the knowledge of light quark dynamics is a key tool for the understanding of the existence of exotic hadrons.
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Valcarce, A., Vijande, J., Richard, J. M., & Garcilazo, H. (2018). Stability of Heavy Tetraquarks. Few-Body Syst., 59(2), 9–7pp.
Abstract: We discuss the stability of tetraquark systems with two different masses. After some reminders about the stability of very asymmetric QQ (q) over bar(q) over bar tetraquarks, we demonstrate that in the all-heavy limit q -> Q, the system becomes unstable for standard color-additive models. We also analyze the consequences of symmetry breaking for Qq (Q) over bar(q) over bar configurations: we find a kind of metastability between the lowest threshold Q (Q) over bar + q (q) over bar and the highest one, Q (q) over bar + (Q) over barq, and we calculate the width of the resonance. Our results are consistent with the experimental observation of narrow hadrons lying well above their lowest decay threshold.
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Vijande, J., & Valcarce, A. (2014). Unraveling the pattern of the XYZ mesons. Phys. Lett. B, 736, 325–328.
Abstract: We present a plausible mechanism for the origin of the XYZ mesons in the heavy meson spectra within a standard quark-model picture. We discuss the conditions required for the existence of four-quark bound states or resonances contributing to the heavy meson spectra, being either compact or molecular. We concentrate on charmonium and bottomonium spectra, where several new states, difficult to understand as simple quark-antiquark pairs, have been reported by different experimental collaborations. The pivotal role played by entangled meson-meson thresholds is emphasized.
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Vijande, J., Valcarce, A., Carames, T. F., & Garcilazo, H. (2013). Heavy Hadron Spectroscopy: A Quark Model Perspective. Int. J. Mod. Phys. E, 22(5), 1330011–25pp.
Abstract: We present recent results of hadron spectroscopy and hadron hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher-order hock space components in the hadron spectra and the connection of this extension with the hadron-hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about the low-energy realization of the theory.
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Vijande, J., Valcarce, A., Carames, T. F., & Garcilazo, H. (2013). Heavy hadron spectroscopy: A quark model perspective. Nucl. Phys. A, 914, 472–481.
Abstract: We present recent results of hadron spectroscopy and hadron-hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher order Fock space components in the hadron spectra and the connection of this extension with the hadron-hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory.
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Vijande, J., Valcarce, A., Carames, T. F., & Richard, J. M. (2014). Multiquark Systems. Few-Body Syst., 55(8-10), 675–681.
Abstract: In this talk we tackle the description of hadron spectroscopy in terms of the constituent quark model. We focus on the mesonic charm sector, where several of the new reported resonances seem to defy their classification as simple quark-antiquark states. We pay special attention to higher order Fock space components in describing excited states of the meson spectra in close connection with the hadron-hadron interaction. The main goal of the present study is a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory.
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Vijande, J., Valcarce, A., & Garcilazo, H. (2015). Constituent-quark model description of triply heavy baryon nonperturbative lattice QCD data. Phys. Rev. D, 91(5), 054011–7pp.
Abstract: This paper provides results for the spectra of triply charmed and bottom baryons based on a constituent-quark model approach. We take advantage of the assumption that potential models are expected to describe triply heavy baryons to a similar degree of accuracy as the successful results obtained in the charmonium and bottomonium sectors. The high precision calculation of the ground state and positive and negative parity excited states recently reported by nonperturbative lattice QCD provides us with a unique opportunity to confront model predictions with the data. This comparison may also help to build a bridge between two difficult to reconcile lattice QCD results, namely, the lattice SU(3) QCD static three-quark potential and the recent results of nonperturbative lattice QCD for the triply heavy baryon spectra.
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Vijande, J., Valcarce, A., & Garcilazo, H. (2014). Heavy-baryon quark model picture from lattice QCD. Phys. Rev. D, 90(9), 094004–6pp.
Abstract: The ground state and excited spectra of baryons containing three identical heavy quarks, b or c, have been recently calculated in nonperturbative lattice QCD. The energy of positive and negative parity excitations has been determined with high precision. Lattice results constitute a unique opportunity to learn about the quark-confinement mechanism as well as elucidating our knowledge about the nature of the strong force. We analyze the nonperturbative lattice QCD results by means of heavy-quark static potentials derived using SU(3) lattice QCD. We make use of different numerical techniques for the three-body problem.
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Vijande, J., Valcarce, A., & Richard, J. M. (2013). Adiabaticity and color mixing in tetraquark spectroscopy. Phys. Rev. D, 87(3), 034040–5pp.
Abstract: We revisit the role of color mixing in the quark model calculation of tetraquark states, and compare simple pairwise potentials to more elaborate string models with three-and four-body forces. We attempt to disentangle the improved dynamics of confinement from the approximations made in the treatment of the internal color degrees of freedom.
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