|
|
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.
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
Aguilar, A. C., Binosi, D., & Papavassiliou, J. (2011). Dynamical equation of the effective gluon mass. Phys. Rev. D, 84(8), 085026–19pp.
Abstract: In this article, we derive the integral equation that controls the momentum dependence of the effective gluon mass in the Landau gauge. This is accomplished by means of a well-defined separation of the corresponding “one-loop dressed” Schwinger-Dyson equation into two distinct contributions, one associated with the mass and one with the standard kinetic part of the gluon. The entire construction relies on the existence of a longitudinally coupled vertex of nonperturbative origin, which enforces gauge invariance in the presence of a dynamical mass. The specific structure of the resulting mass equation, supplemented by the additional requirement of a positive-definite gluon mass, imposes a rather stringent constraint on the derivative of the gluonic dressing function, which is comfortably satisfied by the large-volume lattice data for the gluon propagator, both for SU(2) and SU(3). The numerical treatment of the mass equation, under some simplifying assumptions, is presented for the aforementioned gauge groups, giving rise to a gluon mass that is a nonmonotonic function of the momentum. Various theoretical improvements and possible future directions are briefly discussed.
|
|
|
|
Pierre Auger Collaboration(Abreu, P. et al), & Pastor, S. (2011). Search for first harmonic modulation in the right ascension distribution of cosmic rays detected at the Pierre Auger Observatory. Astropart Phys., 34(8), 627–639.
Abstract: We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5 x 10(17) eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.
|
|
