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Fernandez-Carames, T., Valcarce, A., & Vijande, J. (2010). Charged charmonium molecules. Phys. Rev. D, 82(5), 054032–5pp.
Abstract: We make use of a self-consistent quark-model based study of four-quark charmonium-like states to interpret recent charmonium experimental data. We conclude that there exists a D*(D) over bar* meson-meson molecule with quantum numbers (I-G) J(PC) = (1(-))2(++). Our study confirms the presence of charged charmonium-like resonances on the excited charmonium spectrum. We find support from recent experimental data by the Belle Collaboration [R. Mizuk et al. (Belle Collaboration), Phys. Rev. D 78, 072004 (2008)]. Confirmation of the experimental data by the Belle Collaboration and the determination of the quantum numbers of the new structures would help in discriminating among different theoretical models and would give further support to the theoretical analysis of T. Fernandez-Carames, A. Valcarce, and J. Vijande [Phys. Rev. Lett. 103, 222001 (2009)].
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Richard, J. M., Valcarce, A., & Vijande, J. (2021). Effect of relativistic kinematics on the stability of multiquarks. Phys. Rev. D, 103(5), 054020–8pp.
Abstract: We discuss whether the bound nature of multiquark states in quark models could benefit from relativistic effects on the kinetic energy operator. For mesons and baryons, relativistic corrections to the kinetic energy lead to lower energies, and thus call for a retuning of the parameters of the model. For multiquark states, as well as their respective thresholds, a comparison is made of the results obtained with nonrelativistic and relativistic kinetic energy. It is found that the binding energy is lower in the relativistic case. In particular, QQ (q) over bar(q) over bar tetraquarks with double heavy flavor become stable for a larger ratio of the heavy to light quark masses; the all-heavy tetraquarks QQ (Q) over bar(Q) over bar that are not stable in standard nonrelativistic quark models remain unstable when a relativistic form of kinetic energy is adopted.
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Richard, J. M., Valcarce, A., & Vijande, J. (2017). String dynamics and metastability of all-heavy tetraquarks. Phys. Rev. D, 95(5), 054019–7pp.
Abstract: Multiquark states have been advocated to explain recent experimental data in the heavy-light sector, and there are already speculations about multiquarks containing only heavy quarks and antiquarks. With a rigorous treatment of the four-body problem in current quark models, full-charm (cc (c) over bar(c) over bar) and full-beauty(bb (b) over bar(b) over bar) tetraquarks are found to be unbound. Thus their stability should rely on more subtle effects that are not included in the simple picture of constituent quarks. The case of (bc (b) over bar(c) over bar) might be more favorable if the naive color-additive model of confinement is replaced by a string-inspired interaction.
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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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Zhao, X., McLain, M. A., Vijande, J., Ferrando, A., Carr, L. D., & Garcia-March, M. A. (2019). Nonequilibrium quantum dynamics of partial symmetry breaking for ultracold bosons in an optical lattice ring trap. New J. Phys., 21, 043042–13pp.
Abstract: A vortex in a Bose-Einstein condensate on a ring undergoes quantum dynamics in response to a quantum quench in terms of partial symmetry breaking from a uniform lattice to a biperiodic one. Neither the current, a macroscopic measure, nor fidelity, a microscopic measure, exhibit critical behavior. Instead, the symmetry memory succeeds in identifying the critical symmetry breaking at which the system begins to forget its initial symmetry state. We further identify a symmetry energy difference in the low lying excited states which trends with the symmetry memory.
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