Distribution amplitude for the photon-pion transition

The exclusive production of \pi\pi and \pi\rho in hard \gamma^{\star}\gamma scattering in the forward kinematical region where the virtual photon is highly off-shell are studied through the \gamma\to\pi^- Transition Distribution Amplitudes. The calculation is based on a covariant Bethe-Salpeter approach, applied to the Nambu - Jona-Lasinio model, for the determination of the pion bound state. In particular it is shown that the pion pole contribution produces a large enhancement of the differential cross section for the pion pair production with respect to previous estimates.Comment: To appear in the proceedings of Light Cone 2008: Relativistic Nuclear and Particle Physics (LC2008), Mulhouse, France, 7-11 Jul 200

The Pion-Photon Transition Distribution Amplitudes in the Nambu-Jona Lasinio Model

We define the pion-photon Transition Distribution Amplitudes (TDA) in a field theoretic formalism from a covariant Bethe-Salpeter approach for the determination of the bound state. We apply our formalism to the Nambu - Jona Lasinio model, as a realistic theory of the pion. The obtained vector and axial TDAs satisfy all features required by general considerations. In particular, sum rules and polynomiality condition are explicitly verified. We have numerically proved that the odd coefficients in the polynomiality expansion of the vector TDA vanish in the chiral limit. The role of PCAC and the presence of a pion pole are explicitly shown.Comment: 14 pag. and 6 fig, final version (to appear in Phys. Rev. D

Field evidence of social influence in the expression of political preferences: the case of secessionist flags in Barcelona

Different models of social influence have explored the dynamics of social contagion, imitation, and diffusion of different types of traits, opinions, and conducts. However, few behavioral data indicating social influence dynamics have been obtained from direct observation in `natural' social contexts. The present research provides that kind of evidence in the case of the public expression of political preferences in the city of Barcelona, where thousands of citizens supporting the secession of Catalonia from Spain have placed a Catalan flag in their balconies. We present two different studies. 1) In July 2013 we registered the number of flags in 26% of the the city. We find that there is a large dispersion in the density of flags in districts with similar density of pro-independence voters. However, we find that the density of flags tends to be fostered in those electoral district where there is a clear majority of pro-independence vote, while it is inhibited in the opposite cases. 2) During 17 days around Catalonia's 2013 National Holiday we observed the position at balcony resolution of the flags displayed in the facades of 82 blocks. We compare the clustering of flags on the facades observed each day to equivalent random distributions and find that successive hangings of flags are not independent events but that a local influence mechanism is favoring their clustering. We also find that except for the National Holiday day the density of flags tends to be fostered in those facades where there is a clear majority of pro-independence vote.Comment: 27 pages, 13 figures, 2 table

A ‘basic income’ system could be feasible in Spain, but only by reframing the current debate

Several academics and politicians have argued in favour of a so called ‘basic income’ system, which would provide an unconditional payment to every citizen within a given country to cover basic living costs. José A. Noguera writes on the potential for such a system to solve some of the current issues in Spain. He argues that while the goal of a basic income system is legitimate, it would be extremely difficult to implement this model in practice. Instead he advocates a package of four key reforms which would have the potential to provide most of the benefits of a basic income system for Spanish citizens without alienating those who would be obliged to pay higher taxes

Analysis of infrared optical polishing effluents and reduction of COD and TSS levels by ultrafiltration and coagulation/flocculation

Samples of polishing effluent produced during infrared optics manufacture were analyzed. Their particle size, composition, Zeta potential, chemical oxygen demand (COD), total suspended solids (TSS), and settleable solids were determined. Feasibility of treatment methods such as ultrafiltration (UF) and coagulation/flocculation was investigated to reduce both COD and TSS. It was found that effluents consisted of a suspension of micro- and nanoparticles. Effluent particle size distribution reflected the removal rate of the originating polishing process. Their composition was primarily germanium and other polished substrates as well as polishing abrasives. The effluent Zeta potential was highly negative and prevented particle settling. COD of all specimens was very high, which prevented sewage discharge. Laboratory-scale trials using UF showed substantial COD abatement of up to 74.1%. TSS was reduced to zero after UF. Comparable coagulation/flocculation COD abatement was demonstrated for the highest COD sample

Biodiversidad de Cerambycidae (Coleoptera) en México

ResumenSe presenta un análisis del conocimiento actual de la familia Cerambycidae (Coleoptera) en México. Este análisis se realizó con toda la información publicada en donde se han registrado especies para el país. El número de taxones registrados hasta la fecha para México es de 1 621, incluyendo especies y subespecies. Éstas se encuentran agrupadas en 7 subfamilias, 80 tribus y 454 géneros. Las subfamilias con mayor riqueza de especies son Cerambycinae con 842 y Lamiinae con 609. Respecto a los géneros y tribus, los valores más altos se registran en Cerambycinae con 40 y 215, respectivamente, seguido por Lamiinae con 25 y 177. Las tribus con mayor riqueza son: Elaphidiini con 198, Trachyderini con 177 y Acanthocinini con 137 especies. Los géneros con mayor número de especies son: Eburia Lacordaire con 44, Euderces LeConte con 36 y Phaea Newman con 34. La mayor riqueza en el país se ha registrado en los estados de Veracruz, Oaxaca, Jalisco y Chiapas. La fauna registrada hasta el momento comprende el 4.6% de la fauna mundial de este grupo, 48% de la misma es endémica del país y los datos muestran que la riqueza del país es aún mayor.AbstractAn analysis of the knowledge of the family Cerambycidae (Coleoptera) from Mexico is presented. The data for the analysis were obtained from the literature where records of species from Mexico were published. The taxon number recorded until know is 1 621, including species and subspecies. Those taxa are grouped in 7 subfamilies, 80 tribes and 454 genera. The subfamilies with highest richness are Cerambycinae with 842 species and Lamiinae with 609. About genera and tribes, the highest values are recorded in Cerambycinae with 40 and 215 respectively, followed by Lamiinae with 25 and 177. The tribes with higher richness are Elaphidiiini with 198, Trachyderini with 177 and Acanthocinini with 137 species. The genera with more number of species are: Eburia Lacordaire with 44, Euderces LeConte with 36 and Phaea Newman with 34. The higher richness in the country has been recorded in the states of Veracruz, Oaxaca, Jalisco and Chiapas. The fauna recorded so far comprises 4.6% of the world fauna of this group, 48% of this fauna is endemic to the country and the data analyzed show that the country richness is even graeter

Pion-Photon TDAs in the NJL Model

The pion-photon Transition Distribution Amplitudes (TDAs) are studied, treating the pion as a bound state in the sense of Bethe-Salpeter, in the formalism of the NJL model. The results obtained explicitly verify support, sum rules and polynomiality conditions. The role of PCAC is highlighted.Comment: To appear in the proceedings of International School of Nuclear Physics: 29th Course: Quarks in Hadrons and Nuclei, Erice, Sicily, Italy, 16-24 Sep 200

Modulation Doping near Mott-Insulator Heterojunctions

We argue that interesting strongly correlated two-dimensional electron systems can be created by modulation doping near a heterojunction between Mott insulators. Because the dopant atoms are remote from the carrier system, the electronic system will be weakly disordered. We argue that the competition between different ordered states can be engineered by choosing appropriate values for the dopant density and the setback distance of the doping layer. In particular larger setback distances favor two-dimensional antiferromagnetism over ferromagnetism. We estimate some key properties of modulation-doped Mott insulator heterojunctions by combining insights from Hartree-Fock-Theory and Dynamical-Mean-Field-Theory descriptions and discuss potentially attractive material combinations.Comment: 9 pages, 9 figures, submitte