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Martinez Torres, A., Garzon, E. J., Oset, E., & Dai, L. R. (2011). Limits to the fixed center approximation to Faddeev equations: The case of the phi(2170). Phys. Rev. D, 83(11), 116002–9pp.
Abstract: The fixed center approximation to the Faddeev equations has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper, we study the case of the phi(2170), which has been described by means of Faddeev equations as a resonant state of phi and K (K) over bar, and show the problems derived from the use of the fixed center approximation in its study. At the same time, we also expose the limitations of an alternative approach recently proposed.
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Kaneko, S., Saito, H., Sato, J., Shimomura, T., Vives, O., & Yamanaka, M. (2011). Correlation between flavor-violating decay of long-lived slepton and tau in the coannihilation scenario with the seesaw mechanism. Phys. Rev. D, 83(11), 115005–10pp.
Abstract: We investigate flavor violating decays of the long-lived lightest slepton and the tau lepton in the coannihilation region of the minimal supersymmetric standard model with a seesaw mechanism to generate neutrino masses. We consider a situation where the mass difference between the lightest neutralino, as the lightest supersymmetric particle, and the lightest slepton, as the next-to-lightest supersymmetric particle, is smaller than the mass of tau lepton. In this situation, the lifetime of the lightest slepton is very long and it is determined by lepton flavor violating (LFV) couplings because the slepton mainly consists of the lighter stau and the flavor conserving 2-body decay is kinematically forbidden. We show that the lifetime can change many orders of magnitude by varying the Yukawa couplings entering the seesaw mechanism. We also show that the branching ratios of LFV tau decays are strongly correlated with the lightest slepton lifetime. Therefore the branching ratios of LFV tau decays can be determined or constrained by measuring the slepton lifetime at the LHC experiment.
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Branz, T., Molina, R., & Oset, E. (2011). Radiative decays of the Y(3940), Z(3930), and the X(4160) as dynamically generated resonances. Phys. Rev. D, 83(11), 114015–9pp.
Abstract: We study the radiative decay properties of the charmoniumlike X, Y, and Z mesons generated dynamically from vector-meson-vector-meson interaction in the framework of a unitarized hidden-gauge formalism. In the present work, we calculate the one-and two-photon decay widths of the hidden-charm Y(3940), Z(3930) [or X(3915)], and X(4160) mesons in the framework of the vector-meson dominance formalism. We obtain good agreement with the experiment in case of the two-photon width of the X(3915), which we associate to the 2(+) resonance that we find at 3922 MeV. However, in view of discrepancies with a different approach that also considers the resonances as molecular states, we urge independent calculations along the same lines to further clarify the issue.
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Fabbri, A., & Mayoral, C. (2011). Steplike discontinuities in Bose-Einstein condensates and Hawking radiation: The hydrodynamic limit. Phys. Rev. D, 83(12), 124016–14pp.
Abstract: We present a detailed analytical analysis of the propagation of Bogoliubov phonons on top of Bose-Einstein condensates with spatial and temporal steplike discontinuities in the speed of sound in the hydrodynamic limit. We focus on some features in the correlations patterns, in particular, of density-density correlations. The application to the study of the Hawking signal in the formation of acoustic black hole-like configurations is also discussed.
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Alarcon, J. M., Martin Camalich, J., Oller, J. A., & Alvarez-Ruso, L. (2011). pi N scattering in relativistic baryon chiral perturbation theory reexamined. Phys. Rev. C, 83(5), 055205–14pp.
Abstract: We have analyzed pion-nucleon scattering using the manifestly relativistic covariant framework of infrared regularization up to O(q(3)) in the chiral expansion, where q is a generic small momentum. We describe the low-energy phase shifts with a similar quality as previously achieved with heavy baryon chiral perturbation theory, root s less than or similar to 1.14 GeV. New values are provided for the O(q(2)) and O(q(3)) low-energy constants, which are compared with previous determinations. This is also the case for the scattering lengths and volumes. Finally, we have unitarized the previous amplitudes and as a result the energy range where data are reproduced increases significantly.
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