Yamagata-Sekihara, J., Roca, L., & Oset, E. (2010). Nature of the K-2*(1430), K-3*(1780), K-4*(2045), K-5*(2380), and K-6* as K*-multi-rho states. Phys. Rev. D, 82(9), 094017–8pp.
Abstract: We show that the K-2*(1430), K-3*(1780), K-4*(2045), K-5*(2380), and a not-yet-discovered K-6* resonance are basically molecules made of an increasing number of rho(770) and one K*(892) mesons. The idea relies on the fact that the vector-vector interaction in the s wave with spins aligned is very strong for both rho rho and K*rho. We extend a recent work, where several resonances showed up as multi-rho(770) molecules, to the strange sector including the K*(892) into the system. The resonant structures show up in the multibody scattering amplitudes, which are evaluated in terms of the unitary two-body vector-vector scattering amplitudes by using the fixed center approximation to the Faddeev equations.
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Borja, E. F., Diaz-Polo, J., Garay, I., & Livine, E. R. (2010). Dynamics for a 2-vertex quantum gravity model. Class. Quantum Gravity, 27(23), 235010–34pp.
Abstract: We use the recently introduced U(N) framework for loop quantum gravity to study the dynamics of spin network states on the simplest class of graphs: two vertices linked with an arbitrary number N of edges. Such graphs represent two regions, in and out, separated by a boundary surface. We study the algebraic structure of the Hilbert space of spin networks from the U(N) perspective. In particular, we describe the algebra of operators acting on that space and discuss their relation to the standard holonomy operator of loop quantum gravity. Furthermore, we show that it is possible to make the restriction to the isotropic/homogeneous sector of the model by imposing the invariance under a global U(N) symmetry. We then propose a U(N)-invariant Hamiltonian operator and study the induced dynamics. Finally, we explore the analogies between this model and loop quantum cosmology and sketch some possible generalizations of it.
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Fernandez-Martinez, E., Giordano, G., Mena, O., & Mocioiu, I. (2010). Atmospheric neutrinos in ice and measurement of neutrino oscillation parameters. Phys. Rev. D, 82(9), 093011–7pp.
Abstract: The main goal of the IceCube Deep Core array is to search for neutrinos of astrophysical origins. Atmospheric neutrinos are commonly considered as a background for these searches. We show that the very high statistics atmospheric neutrino data can be used to obtain precise measurements of the main oscillation parameters.
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Llosa, G., Barrio, J., Lacasta, C., Bisogni, M. G., Del Guerra, A., Marcatili, S., et al. (2010). Characterization of a PET detector head based on continuous LYSO crystals and monolithic, 64-pixel silicon photomultiplier matrices. Phys. Med. Biol., 55(23), 7299–7315.
Abstract: The characterization of a PET detector head based on continuous LYSO crystals and silicon photomultiplier (SiPM) arrays as photodetectors has been carried out for its use in the development of a small animal PET prototype. The detector heads are composed of a continuous crystal and a SiPM matrix with 64 pixels in a common substrate, fabricated specifically for this project. Three crystals of 12 mm x 12 mm x 5 mm size with different types of painting have been tested: white, black and black on the sides but white on the back of the crystal. The best energy resolution, obtained with the white crystal, is 16% FWHM. The detector response is linear up to 1275 keV. Tests with different position determination algorithms have been carried out with the three crystals. The spatial resolution obtained with the center of gravity algorithm is around 0.9 mm FWHM for the three crystals. As expected, the use of this algorithm results in the displacement of the reconstructed position toward the center of the crystal, more pronounced in the case of the white crystal. A maximum likelihood algorithm has been tested that can reconstruct correctly the interaction position of the photons also in the case of the white crystal.
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Gamermann, D., Nieves, J., Oset, E., & Ruiz Arriola, E. (2010). Couplings in coupled channels versus wave functions: Application to the X(3872) resonance. Phys. Rev. D, 81(1), 014029–14pp.
Abstract: We perform an analytical study of the scattering matrix and bound states in problems with many physical coupled channels. We establish the relationship of the couplings of the states to the different channels, obtained from the residues of the scattering matrix at the poles, with the wave functions for the different channels. The couplings basically reflect the value of the wave functions around the origin in coordinate space. In the concrete case of the X(3872) resonance, understood as a bound state of D-0(D) over bar*(0) and D+D*(-) (and c.c. From now on, when we refer to D-0(D) over bar*(0), D+D*(-), or D (D) over bar* we are actually referring to the combination of these states with their complex conjugate in order to form a state with positive C-parity), with the D-0(D) over bar*(0) loosely bound, we find that the couplings to the two channels are essentially equal leading to a state of good isospin I = 0 character. This is in spite of having a probability for finding the D-0(D) over bar*(0) state much larger than for D+D*(-) since the loosely bound channel extends further in space. The analytical results, obtained with exact solutions of the Schrodinger equation for the wave functions, can be useful in general to interpret results found numerically in the study of problems with unitary coupled channels methods.
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