Bottoni, S. et al, Gadea, A., & Perez-Vidal, R. M. (2024). Search for the γ decay of the narrow near-threshold proton resonance in 11B. Phys. Lett. B, 855, 138851–4pp.
Abstract: The y decay of the elusive narrow, near-threshold proton resonance in 11 B was investigated at Laboratori Nazionali di Legnaro (INFN) in a particle-y coincidence experiment, using the 6 Li( 6 Li,py) fusion-evaporation reaction and the GALILEO-GALTRACE setup. No clear signature was found for a possible E1 decay to the 1/2-1, – 1 , first-excited state of 11 B, predicted by the Shell Model Embedded in the Continuum (SMEC) with a branching of 0.98+167 +167 -69 x 10-3 -3 with respect to the dominant particle-decaying modes. The statistical analysis of the y-ray spectrum provided an average upper limit of 2.37 x 10-3 -3 for this y-ray branching, with a global significance of 5 sigma. On the other hand, by imposing a global confidence level of 3 sigma, a significant excess of counts was observed for Ey y = 9300(20) keV, corresponding to a resonance energy of 11429(20) keV (namely 200(20) keV above the proton separation energy of 11 B) and a y-ray branching of 1.12(35) x10-3. -3 . This result is compatible with the SMEC calculations, potentially supporting the existence of a near-threshold proton resonance in 11 B.
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Tolos, L., Cabrera, D., Garcia-Recio, C., Molina, R., Nieves, J., Oset, E., et al. (2013). Strangeness and charm in nuclear matter. Nucl. Phys. A, 914, 461–471.
Abstract: The properties of strange (K, (K) over bar and (K) over bar*) and open-charm (D, (D) over bar and D*) mesons in dense matter are studied using a unitary approach in coupled channels for meson-baryon scattering. In the strangeness sector, the interaction with nucleons always comes through vector-meson exchange, which is evaluated by chiral and hidden gauge Lagrangians. For the interaction of charmed mesons with nucleons we extend the SU(3) Weinberg-Tomozawa Lagrangian to incorporate spin-flavor symmetry and implement a suitable flavor symmetry breaking. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects and meson self-energies. On one hand, we obtain the K, (K) over bar and (K) over bar* spectral functions in the nuclear medium and study their behaviour at finite density, temperature and momentum. We also make an estimate of the transparency ratio of the gamma A -> K+ K*(-) A' reaction, which we propose as a tool to detect in-medium modifications of the (K) over bar* meson. On the other hand, in the charm sector, several resonances with negative parity are generated dynamically by the s-wave interaction between pseudoscalar and vector meson multiplets with 1/2(+) and 3/2(+) baryons. The properties of these states in matter are analyzed and their influence on the open-charm meson spectral functions is studied. We finally discuss the possible formation of D-mesic nuclei at FAIR energies.
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Romanets, O., Tolos, L., Garcia-Recio, C., Nieves, J., Salcedo, L. L., & Timmermans, R. (2013). Heavy-quark spin symmetry for charmed and strange baryon resonances. Nucl. Phys. A, 914, 488–493.
Abstract: We study charmed and strange odd-parity baryon resonances that are generated dynamically by a unitary baryon-meson coupled-channels model which incorporates heavy-quark spin symmetry. This is accomplished by extending the SU(3) Weinberg-Tomozawa chiral Lagrangian to SU(8) spin-flavor symmetry plus a suitable symmetry breaking. The model generates resonances with negative parity from the s-wave interaction of pseudoscalar and vector mesons with 1/2(+) and 3/2(+) baryons in all the isospin, spin, and strange sectors with one, two, and three charm units. Some of our results can be identified with experimental data from several facilities, such as the CLEO, Belle, or BaBar Collaborations, as well as with other theoretical models, whereas others do not have a straightforward identification and require the compilation of more data and also a refinement of the model. (c) 2013 Elsevier B.V. All rights reserved.
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Lutz, M. F. M. et al, & Nieves, J. (2016). Resonances in QCD. Nucl. Phys. A, 948, 93–105.
Abstract: We report on the EMMI Rapid Reaction Task Force meeting 'Resonances in QCD', which took place at GSI October 12-14,2015. A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions: What is needed to understand the physics of resonances in QCD? Where does QCD lead us to expect resonances with exotic quantum numbers? What experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with up, down and strange quark content were considered. For heavy-light and heavy-heavy meson systems, those with charm quarks were the focus. This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.
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Kamiya, Y., Miyahara, K., Ohnishi, S., Ikeda, Y., Hyodo, T., Oset, E., et al. (2016). Antikaon-nucleon interaction and Lambda(1405) in chiral SU(3) dynamics. Nucl. Phys. A, 954, 41–57.
Abstract: The properties of the Lambda(1405) resonance are key ingredients for determining the antikaon-nucleon interaction in strangeness nuclear physics, and the novel internal structure of the Lambda(1405) is of great interest in hadron physics, as a prototype case of a baryon that does not fit into the simple three-quark picture. We show that a quantitative description of the antikaon-nucleon interaction with the Lambda(1405) is achieved in the framework of chiral SU(3) dynamics, with the help of recent experimental progress. Further constraints on the (K) over barN subthreshold interaction are provided by analyzing pi Sigma spectra in various processes, such as the K(-)d -> pi Sigma n reaction and the Lambda(c) -> pi pi Sigma decay. The structure of the Lambda(1405) is found to be dominated by an antikaon-nucleon molecular configuration, based on its wavefunction derived from a realistic (K) over barN potential and the compositeness criteria from a model-independent weak-binding relation.
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