Central pseudoscalar production in pp scattering and the gluon contribution to the proton spin

Central pseudoscalar production in $pp$ scattering is suppressed at small values of $Q_\perp$, where $Q$ is defined as the difference between the momenta transferred from the two protons. Such a behaviour is expected if the production occurs through the fusion of two vectors. Photon exchange could provide the dominant contribution at low transferred momenta, but we argue that an extension of the experiment could probe the gluon contribution to the proton spin.Comment: 12 pages, 2 figures and 3 tables, uses epsf.sty. Added references and tables. Minor changes include

Study of the eta-eta' system in the two mixing angle scheme

An analysis of various decay processes is performed using the two mixing angle description of the $\eta$-$\eta^\prime$ system, incorporating the link to the gluonic sector through anomalies. The agreement is excellent. For comparison with previous works, our results are expressed both in the ``octet-singlet'' and in the ``quark-flavour'' basis. It turns out that at the present experimental accuracy, the two angles are significantly different in the former, but not in the latter basis. The implications of our analysis for the Large $N_c$ $\chi$PT predictions are also discussed.Comment: 15 pages, JHEP style. Comments on the VMD description of the VPgamma decays, the error correlations,the scale dependence of f0, and the implications of the analysis for Large Nc ChpT are include

Kelp gull ( <i>Larus dominicanus</i> ) as a carrier of pathogens in the patagonian coast

En este trabajo se estudió el transporte de enterobacterias por parte de la gaviota cocinera (<i>Larus dominicanus</i>), en un sector de la costa patagónica. A lo largo de un año (1995-96), un total de 100 individuos de distinto sexo y clase de edad, fueron capturados en el basural pesquero de Puerto Deseado. A cada uno de ellos se le realizó un hisopado cloacal y el sexo fue determinado por disección en el laboratorio. El análisis bacteriológico fue realizado por medio de pruebas bioquímicas convencionales, determinándose la presencia de al menos 10 especies de enterobacterias pertenecientes a los géneros: <i>Escherichia, Proteus, Citrobacter, Salmonella, Hafnia, Shigella, Enterobacter y Yersinia</i>. No se hallaron diferencias en las tasas de prevalencia entre sexos y clases de edades. La presencia de patógenos, para el hombre ó el ganado, en el tracto intestinal de las gaviotas a lo largo del año no mostró grandes diferencias, salvo para Proteus, que tuvo un pico de presencia durante la primavera y el verano y Citrobacter, durante la primavera. Salmonella typhimurium representa la entero bacteria encontrada de mayor riesgo para el hombre y el ganado y fue registrada durante gran parte del año. Aunque en el presente estudio no se investigan las tasas de infección bacteriana en humanos o ganado, la abundancia de gaviotas cocineras, sus hábitos alimenticios y la ubicación relativa de la ciudad (entre las colonias y el basural), convierten a estas aves en un probable candidato como vector de patógenos. Palabras Claves: Gaviotas, Larus dominicanus, enterobacterias, basurales, residuos, PatagoniaIn this paper we analyzed the carriage of pathogens by Kelp gulls (Larus dominicanus) in a portion of the Patagonian coast. During one year (1995-96), 100 individual s of different sex and age class were caught at fisheries tip of Puerto Deseado. Faecal samples were obtained from individual birds by cloacal swab and sex was determined at laboratory by dissection. We registered at least ten species of bacteria of eight genus (Escherichia, Proteus, Citrobacter, Salmonella, Hafnia, Shigella, Enterobacter and Yersinia), using standard biochemical technics. There were no differences in carriage rates between sexes and age classes. Camage rates were similar over almost all year, but Citrobacter was more abundant during Spring and Proteus during Spring and Summer. Salmonella typhimurium represents the more risky species for cattle and humans and it was found during most of the year. Despite this study was not focused to investigate the infection rates in humans or cattle, the abundance of kelp gulls, its pattems of feeding and movements, the relative location of the city (between fisheries tip and breeding areas), makes the species a very likely candidate for a pathogens vector

SUSY dark matter(s)

We review here the status of different dark matter candidates in the context of supersymmetric models, in particular the neutralino as a realization of the WIMP-mechanism and the gravitino. We give a summary of the recent bounds in direct and indirect detection and also of the LHC searches relevant for the dark matter question. We discuss also the implications of the Higgs discovery for the supersymmetric dark matter models and give the prospects for the future years.Comment: 16 pages, 3 figure

Incidental capture of seabirds in Argentinean side-haul trawlers

Between April 2008 and July 2015, we conducted a total of 18 trips on five different side-haul trawlers fishing within the Argentine Exclusive Economic Zone, monitoring 486 hauls. We observed 100% of the hauls and monitored trawl cables for 136.7 hours, about 5% of the trawl effort, to identify the levels of seabird bycatch from net entanglements and collisions with trawl cables. A total of 35 net entanglements of White-chinned Petrels Procellaria aequinoctialis, Great Shearwaters Ardenna gravis, Black-browed Albatrosses Thalassarche melanophris and Southern Royal Albatross Diomedea epomophora were recorded, all of which occurred during the autumn and winter. Additionally, 656 seabird collisions against trawl cables were recorded including 39 heavy, 96 medium and 521 light. Further, we recorded nine Black-browed Albatrosses and two Great Shearwaters potentially dead. Although in the study fishery the number of deaths in the trawl cables could surpass the number of birds incidentally killed in nets, the mortality rate caused by the latter type of interaction far exceeds those observed in nets from other trawl fisheries operating in the Patagonian Shelf. Fortunately, 26% of the seabirds entangled in the net were recovered and released alive, which indicates that awareness and training in safe bird handling and release may improve captured seabird survival rates. The main objectives of this work is to highlight a little-studied source of seabird mortality by entanglement, to generate discussion on potential technical mitigation measures for side-haul trawl fisheries, and to propose crew training in safe handling and release of seabirds as an immediate mitigation measure.Fil: Tamini, Leandro Luis. Albatross Task Force Argentina; ArgentinaFil: Chavez, Leandro Nahuel. Albatross Task Force Argentina; ArgentinaFil: Dellacasa, R. F.. Albatross Task Force Argentina; ArgentinaFil: Crawford, R.. Birdlife International; Reino Unido. Royal Society For The Protection Of Birds; Reino UnidoFil: Frere, Esteban. Birdlife International; Reino Unido. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

FCNC in left-right symmetric theories and constraints on the right-handed scale

We revise the limits on the FCNC higgses in manifestly left-right symmetric theories. It is shown that the combination of the Kobayashi-Maskawa CP-violation with the tree level $\Delta S=2$ higgs exchange gives very large contribution to the CP-violating $\epsilon$ parameter. It leads to the new strong constraint on the FCNC higgs mass, M>50- 100 TeV, enhanced by factor of the order $\sqrt{m_t/m_c}$. Being addressed to the supersymmetric left-right models, FCNC problem requires both right-handed scale and supersymmetric mass parameters be heavier than 50 TeV for $tan\beta\sim 1$. The most relaxed case corresponds to $tan\beta\sim 20- 30$ where right-handed scale can be of the order of few TeV.Comment: 11 pages, latex, 3 figure

Enhanced baryon number violation due to cosmological defects with localized fermions along extra dimension

We propose a new scenario of baryon number violation in models with extra dimensions. In the true vacuum, baryon number is almost conserved due to the localization mechanism of matter fields, which suppresses the interactions between quarks and leptons. We consider several types of cosmological defects in four-dimensional spacetime that shift the center of the localized matter fields, and show that the magnitudes of the baryon number violating interactions are well enhanced. Application to baryogenesis is also discussed.Comment: 12pages, latex2e, added references, to appear in PR

Angular Momentum Conservation Law for Randall-Sundrum Models

In Randall-Sundrum models, by the use of general Noether theorem, the covariant angular momentum conservation law is obtained with the respect to the local Lorentz transformations. The angular momentum current has also superpotential and is therefore identically conserved. The space-like components $J_{ij}$ of the angular momentum for Randall-Sundrum models are zero. But the component $J_{04}$ is infinite.Comment: 10 pages, no figures, accepted by Mod. Phys. Lett.