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Garcia-Recio, C., Nieves, J., Salcedo, L. L., & Tolos, L. (2012). D- mesic atoms. Phys. Rev. C, 85(2), 025203–13pp.
Abstract: The anti-D meson self-energy is evaluated self-consistently, using unitarized coupled-channel theory, by computing the in-medium meson-baryon T matrix in the C = -1, S = 0 sector. The heavy pseudo-scalar and heavy vector mesons, (D) over bar and (D) over bar*, are treated on equal footing as required by heavy-quark spin symmetry. Results for energy levels and widths of (D) over bar (-) mesic atoms in C-12, Ca-40, Sn-118, and Pb-208 are presented. The spectrum contains states of atomic and of nuclear types for all nuclei. (D) over bar (0)-nucleus bound states are also obtained. We find that, after electromagnetic and nuclear cascade, these systems end up with the (D) over bar bound in the nucleus, either as a meson or as part of an exotic (D) over barN (pentaquark) loosely bound state.
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Garcia-Recio, C., Hidalgo-Duque, C., Nieves, J., Salcedo, L. L., & Tolos, L. (2015). Compositeness of the strange, charm, and beauty odd parity Lambda states. Phys. Rev. D, 92(3), 034011–14pp.
Abstract: We study the dependence on the quark mass of the compositeness of the lowest-lying odd parity hyperon states. Thus, we pay attention to Lambda-like states in the strange, charm, and beauty sectors which are dynamically generated using a unitarized meson-baryon model. In the strange sector we use a SU(6) extension of the Weinberg-Tomozawa meson-baryon interaction, and we further implement the heavy-quark spin symmetry to construct the meson-baryon interaction when charmed or beauty hadrons are involved. In the three examined flavor sectors, we obtain two J(P) = 1/2- and one J(P) = 3/2(-) Lambda states. We find that the. states which are bound states (the three Lambda(b)) or narrow resonances [one Lambda(1405) and one Lambda(c)(2595)] are well described as molecular states composed of s-wave meson-baryon pairs. The 1/2(-) wide Lambda(1405) and Lambda(c)(2595) as well as the 3/2(-) Lambda(1520) and Lambda(c)(2625) states display smaller compositeness so they would require new mechanisms, such as d-wave interactions.
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Yao, D. L., Fernandez-Soler, P., Guo, F. K., & Nieves, J. (2020). New parametrization of the form factors in (B)over-bar -> Dl(nu)over-bar(l) decays. Phys. Rev. D, 101(3), 034014–7pp.
Abstract: A new model-independent parametrization is proposed for the hadronic form factors in the semileptonic (B) over bar -> Dl (nu) over bar (l) decay. By a combined consideration of the recent experimental and lattice QCD data, we determine precisely the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-cb vertical bar = 41.01(75) x 10(-3) and the ratio R-D = BR((B) over bar -> D tau(nu) over bar (tau))/BR((B) over bar -> Dl (nu) over bar (l)) = 0.301(5). The coefficients in this parametrization, related to phase shifts by sumrulelike dispersion relations and hence called phase moments, encode important scattering information of the (B) over bar (D) over bar interactions which are poorly known so far. Thus, we give strong hints about the existence of at least one bound and one virtual (B) over bar (D) over bar S-wave 0(+) states, subject to uncertainties produced by potentially sizable inelastic effects. This formalism is also applicable for any other semileptonic processes induced by the weak b -> c transition.
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Garcia-Recio, C., Nieves, J., Romanets, O., Salcedo, L. L., & Tolos, L. (2013). Odd parity bottom-flavored baryon resonances. Phys. Rev. D, 87(3), 034032–9pp.
Abstract: The LHCb Collaboration has recently observed two narrow baryon resonances with beauty. Their masses and decay modes look consistent with the quark model orbitally excited states Lambda(b)(5912) and Lambda(b)*(5920), with quantum numbers J(P) = 1/2(-) and 3/2(-), respectively. We predict the existence of these states within a unitarized meson-baryon coupled-channel dynamical model, which implements heavy-quark spin symmetry. Masses, quantum numbers and couplings of these resonances to the different meson-baryon channels are obtained. We find that the resonances Lambda(0)(b)(5912) and Lambda(0)(b)(5920) are heavy-quark spin symmetry partners, which naturally explains their approximate mass degeneracy. Corresponding bottom-strange baryon resonances are predicted at Xi(b)(6035.4) (J(P) = 1/2(-)) and Xi(b)(6043.3) (J(P) = 3/2(-)). The two Lambda(b) and two Xi(b) resonances complete a multiplet of the combined symmetry SU(3)-flavor times heavy-quark spin.
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Albaladejo, M., Nieves, J., & Tolos, L. (2021). D(D)over-bar* scattering and chi(c1) (3872) in nuclear matter. Phys. Rev. C, 104(3), 035203–20pp.
Abstract: We study the behavior of the chi(c1) (3872), also known as X(3872), in dense nuclear matter. We begin from a picture in vacuum of the X(3872) as a purely molecular (D (D) over bar*-c.c.) state, generated as a bound state from a heavy-quark symmetry leading-order interaction between the charmed mesons, and analyze the D (D) over bar* scattering T matrix (T-D (D) over bar*) inside of the medium. Next, we consider also mixed-molecular scenarios and, in all cases, we determine the corresponding X(3872) spectral function and the D (D) over bar* amplitude, with the mesons embedded in the dense environment. We find important nuclear corrections for T-D (D) over bar* and the pole position of the resonance, and discuss the dependence of these results on the D (D) over bar* molecular component in the X(3872) wave function. These predictions could be tested in the finite-density regime that can be accessed in the future CBM and PANDA experiments at the Facility for Antiproton and Ion Research (FAIR).
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