Dias, J. M., Debastiani, V. R., Roca, L., Sakai, S., & Oset, E. (2017). Binding of the BD(D)over-bar and BDD systems. Phys. Rev. D, 96(9), 094007–6pp.
Abstract: We study theoretically the BD (D) over bar and BDD systems to see if they allow for possible bound or resonant states. The three-body interaction is evaluated implementing the fixed center approximation to the Faddeev equations which considers the interaction of a D or (D) over bar particle with the components of a BD cluster, previously proved to form a bound state. We find an I(J(P)) = 1/2(0(-)) bound state for the BD (D) over bar system at an energy around 8925-8985 MeV within uncertainties, which would correspond to a bottom hidden-charm meson. In contrast, for the BDD system, which would be bottom double-charm and hence manifestly exotic, we have found hints of a bound state in the energy region 8935-8985 MeV, but the results are not stable under the uncertainties of the model, and we cannot assure, nor rule out, the possibility of a BDD three-body state.
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Dai, L. R., Roca, L., & Oset, E. (2020). Tau decay into tau(t) and a(1)(1260), b(1)(1235), and two K-1(1270). Eur. Phys. J. C, 80(7), 673–9pp.
Abstract: We study the tau -> nu(tau). A decay, with A an axialvector meson. We produce the a(1) (1260) and b(1) (1235) resonances in the Cabibbo favored mode and two K-1 (1270) states in the Cabibbo suppressed mode. We take advantage of previous chiral unitary approach results where these resonances appear dynamically from the vector and pseudoscalar meson interaction in s-wave. Actually two different poles were obtained associated to the K-1(1270) quantum numbers. We find that the unmeasured rates for b(1)(1235) production are similar to those of the a(1)(1260) and for the two K-1 states we suggest to separate the present information on the (K) over bar pi pi invariant masses into (K) over bar*pi and rho K modes, the channels to which these two resonances couple most strongly, predicting that thesemodes peak at different energies and have different widths. These measurements should shed light on the existence of these two K-1 states. In addition, we have gone one step further making a comparison with experimental results of three meson decay channels, letting the vector mesons of our approach decay into pseudoscalars, and we find an overall good agreement with experiment.
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Dai, L. R., Oset, E., Feijoo, A., Molina, R., Roca, L., Martinez Torres, A., et al. (2022). Masses and widths of the exotic molecular B-(s)(()*B-)((s))(*()) states. Phys. Rev. D, 105(7), 074017–11pp.
Abstract: We study the interaction of the doubly bottom systems BB, B*B, BsB, B-s*B, B*B*, B*B-S, B*B-s*, BsBs, BsBs*, B-s*B-s* by means of vector meson exchange with Lagrangians from an extension of the local hidden gauge approach. The full s-wave scattering matrix is obtained implementing unitarity in coupled channels by means of the Bethe-Salpeter equation. We find poles below the channel thresholds for the attractively interacting channels B*B in I = 0, B-s*B – B*B-s in I = 1/2, B* B* in I = 0, and B-s*B* in I = 1/2, all of them with J(P) = 1(+). For these cases the widths are evaluated identifying the dominant source of imaginary part. We find binding energies of the order of 10-20 MeV, and the widths vary much from one system to the other: of the order of 10-100 eV for the B* B system and B-s*B – B* B-s, about 6 MeV for the B*B* system and of the order of 0.5 MeV for the B-s*B* system.
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Roca, L., Liang, W. H., & Oset, E. (2022). Inconsistency of the data on the K-1(1270) -> pi K-0*(1430) decay width. Phys. Lett. B, 824, 136827–3pp.
Abstract: We show, using the same Lagrangian for the K-1(1270) -> pi K-0*(1430) and K-0*(1430) -> K-1 (1270)pi decays, that the present PDG data on the partial decay width of K-1 (1270) -> pi K-0*(1430) implies a width for K-0*(1430) -> K-1 (1270)pi decay which is about one order of magnitude larger than the total K-0*(1430) width. A discussion on this inconsistency is done, stressing its relationship to the existence of two K-1(1270) states obtained with the chiral unitary theory, which are not considered in the experimental analyses of K pi pi data.
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Roca, L., & Oset, E. (2017). Role of a triangle singularity in the pi Delta decay of N(1700)(3/2(-)). Phys. Rev. C, 95(6), 065211–8pp.
Abstract: We show the important role played by the pi Delta(1232) channel in the build up of the N(1700)(3/2(-)) resonance due to the nontrivial enhancement produced by a singularity of a triangular loop. The N(1700) is one of the dynamically generated resonances produced by the coupled-channel vector-baryon interaction. The pi Delta channel was neglected in previous works but we show that it has to be incorporated into the coupled-channel formalism due to an enhancement produced by a singularity in the triangular loop with., nucleon, and p as internal loop lines and pi and Delta as external ones. The enhancement is of nonresonant origin but it contributes to the dynamical generation of the N(1700) resonance due to the nonlinear dynamics involved in the coupled-channel mechanisms. We obtain an important increase of the total width of the N(1700) resonance when the pi Delta channel is included and provide predictions for the partial widths of the N(1700) decays into VB and pi Delta.
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