Dias, J. M., Yu, Q. X., Liang, W. H., Sun, Z. F., Xie, J. J., & Oset, E. (2020). Xi(bb) and Omega(bbb) molecular states. Chin. Phys. C, 44(6), 064101–8pp.
Abstract: Using the vector exchange interaction in the local hidden gauge approach, which in the light quark sector generates the chiral Lagrangians and has produced realistic results for Omega(C), Xi(c), Xi(b) and the hidden charm pentaquark states, we study the meson-baryon interactions in the coupled channels that lead to the Xi(bb) and Omega(bbb) excited states of the molecular type. We obtain seven states of the Xi(bb) type with energies between and MeV, and one Omega(bbb) state at MeV.
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Doring, M., Meissner, U. G., Oset, E., & Rusetsky, A. (2011). Unitarized Chiral Perturbation Theory in a finite volume: Scalar meson sector. Eur. Phys. J. A, 47(11), 139–15pp.
Abstract: We develop a scheme for the extraction of the properties of the scalar mesons f(0)(600), f(0)(980), and a(0)(980) from lattice QCD data. This scheme is based on a two-channel chiral unitary approach with fully relativistic propagators in a finite volume. In order to discuss the feasibility of finding the mass and width of the scalar resonances, we analyze synthetic lattice data with a fixed error assigned, and show that the framework can be indeed used for an accurate determination of resonance pole positions in the multichannel scattering.
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Doring, M., Meissner, U. G., Oset, E., & Rusetsky, A. (2012). Scalar mesons moving in a finite volume and the role of partial wave mixing. Eur. Phys. J. A, 48(8), 114–18pp.
Abstract: Phase shifts and resonance parameters can be obtained from finite-volume lattice spectra for interacting pairs of particles, moving with non-zero total momentum. We present a simple derivation of the method that is subsequently applied to obtain the pi pi and pi K phase shifts in the sectors with total isospin I – 0 and I – 1/2, respectively. Considering different total momenta, one obtains extra data points for a given volume that allow for a very efficient extraction of the resonance parameters in the infinite-volume limit. Corrections due to the mixing of partial waves are provided. We expect that our results will help to optimize the strategies in lattice simulations, which aim at an accurate determination of the scattering and resonance properties.
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Doring, M., Oset, E., & Meissner, U. G. (2010). Evaluation of the polarization observables I-S and I-C in the reaction gamma p -> pi(0)eta p. Eur. Phys. J. A, 46(2), 315–323.
Abstract: We evaluate the polarization observables I-S and I-C for the reaction gamma p -> pi(0)eta p, using a chiral unitary framework developed earlier. The I-S and I-C observables have been recently measured for the first time by the CBELSA/TAPS Collaboration. The theoretical predictions of I-S and I-C, given for altogether 18 angle-dependent functions, are in good agreement with the measurements. Also, the asymmetry d Sigma/dcos theta evaluated here agrees with the data. We show the importance of the Delta(1700) D-33-resonance and its S-wave decay into eta Delta(1232). The result can be considered as a further confirmation of the dynamical nature of this resonance. At the highest energies, deviations of the predictions from the data start to become noticeable, which leaves room for additional processes and resonances such as a Delta(1940) D-33. We also point out how to further improve the calculation.
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Doring, M., Jido, D., & Oset, E. (2010). Helicity amplitudes of the Lambda(1670) and two Lambda(1405) as dynamically generated resonances. Eur. Phys. J. A, 45(3), 319–333.
Abstract: We determine the helicity amplitudes A(1/2) and radiative decay widths in the transition Lambda(1670) -> gamma Y (Y = Lambda or Sigma(0)). The Lambda(1670) is treated as a dynamically generated resonance in meson-baryon chiral dynamics. We obtain the radiative decay widths of the Lambda(1670) to gamma Lambda as 2 +/- 1 keV and to -gamma Sigma(0) as 120 +/- 50 keV. Also, the Q(2)-dependence of the helicity amplitudes A(1/2) is calculated. We find that the K Xi component in the Lambda(1670) structure, mainly responsible for the dynamical generation of this resonance, is also responsible for the significant suppression of the decay ratio Gamma(gamma A)/Gamma(gamma Sigma 0). A measurement of the ratio would, thus, provide direct access to the nature of the Lambda(1670). To compare the result for the Lambda(1670), we calculate the helicity amplitudes Lambda(1/2) for the two states of the Lambda(1405). Also, the analytic continuation of Feynman parameterized integrals of more complicated loop amplitudes to the complex plane is developed which allows for an internally consistent evaluation of A(1/2).
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