Role of resonances in rho^0 -> pi^+ pi^- gamma

We study the effect of the sigma(600) and a_1(1260) resonances in the rho^0 -> pi^+ pi^- gamma decay, within the meson dominance model. Major effects are driven by the mass and width parameters of the sigma(600), and the usually neglected contribution of the a_1(1260), although small by itself, may become sizable through its interference with pion bremsstrahlung, and the proper relative sign can favor the central value of the experimental branching ratio. We present a procedure, using the gauge invariant structure of the resonant amplitudes, to kinematically enhance the resonant effects in the angular and energy distribution of the photon. We also elaborate on the coupling constants involved.Comment: 5 pages, 5 figures, accepted for publication in PR

A class of Hamilton-Jacobi equations on Banach-Finsler manifolds

The concept of subdifferentiability is studied in the context of $C^1$ Finsler manifolds (modeled on a Banach space with a Lipschitz $C^1$ bump function). A class of Hamilton-Jacobi equations defined on $C^1$ Finsler manifolds is studied and several results related to the existence and uniqueness of viscosity solutions are obtained.Comment: 24 page

Modeling state-selective photodetachment in cold ion traps: Rotational state "crowding" in small anions

Using accurate ab initio calculations of the interaction forces, we employ a quantum mechanical description of the collisional state-changing processes that occur in a cold ion trap with He as a buffer gas. We generate the corresponding inelastic rates for rotational transitions involving three simple molecular anions OH−(1Σ), MgH−(1Σ), and C2H−(1Σ) colliding with the helium atoms of the trap. We show that the rotational constants of these molecular anions are such that within the low-temperature regimes of a cold ion trap (up to about 50 K), a different proportion of molecular states are significantly populated when loading helium as a buffer gas in the trap. By varying the trap operating conditions, population equilibrium at the relevant range of temperatures is reached within different time scales. In the modeling of the photodetachment experiments, we analyze the effects of varying the chosen values for photodetachment rates as well as the laser photon fluxes. Additionally, the changing of the collision dynamics under different buffer gas densities is examined and the best operating conditions, for the different anions, for yielding higher populations of specific rotational states within the ion traps are extracted. The present modeling thus illustrates possible preparation of the trap conditions for carrying out more efficiently state-selected experiments with the trapped anions

Antilisterial and physical properties of biopolymer films containing lactic acid bacteria

Novel biopolymer films were developed and used to control Listeria innocua in an artificially contaminated synthetized medium. Two hydrocolloids, sodium caseinate (NaCas) and methylcellulose (MC), and two bacteriocin-producing lactic acid bacteria (LAB), Lactobacillus acidophilus and Lactobacillus reuteri, were tested. Bioactive cultures were added directly to the film forming solution and films were obtained by casting. In order to study the impact of the incorporation of bacterial cells into the biopolymer matrix, the water vapour permeability, optical and mechanical properties of the dry films were evaluated. Furthermore, the survival of LAB and the antimicrobial potential of bioactive films against L. innocua were studied. Results showed that the use of lactic acid bacteria altered the film s physical properties. Films enriched with bacterial cells exhibit higher gloss and transparency whereas no significant modifications were observed in terms of tensile properties. These films were less-effective water vapour barriers, since a significant increase can be observed in the WVP values. As far as food safety is concerned, these films are an interesting, novel approach. In refrigeration conditions, these films permit a complete inhibition of L. innocua for a week. Viability of LAB was higher in sodium caseinate films, although bacteriocin production was greater in polysaccharide matrix. The best results were obtained for films made of methylcellulose, without differences between the two lactic acid bacteria tested.The authors acknowledge the financial support from Spanish Ministerio de Educacion y Ciencia throughout the project AGL201020694. Author L. Sgnchez-Gonzalez thanks the support of Campus de Excelencia Internacional from Universidad Politecnica de Valencia.Sanchez-Gonzalez, L.; Quintero Saavedra, JI.; Chiralt, A. (2014). Antilisterial and physical properties of biopolymer films containing lactic acid bacteria. Food Control. 35(1):200-206. https://doi.org/10.1016/j.foodcont.2013.07.001S20020635