7,272 research outputs found

    Radiative vector meson decay

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    We study the radiative ρ\rho, ω\omega and ϕ\phi decay into π0π0γ\pi^0 \pi^0 \gamma and π0ηγ\pi^0 \eta \gamma taking into account mechanisms in which there are two sequential vector-vector-pseudoscalar or axial-vector--vector--pseudoscalar steps followed by the coupling of a vector meson to the photon, considering the final state interaction of the two mesons. Other mechanisms in which two kaons are produced through the same sequential mechanisms or from vector meson decay into two kaons which undergo final state interaction leading to the final pair of pions or π0η\pi^0 \eta, are also considered. The results of the parameter free theory, together with the theoretical uncertainties, are compared with the latest experimental results at Frascati and Novosibirsk.Comment: Prepared for the 10th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleo

    Chiral Dynamics of scalar mesons: radiative ϕ\phi decay and σ\sigma in the medium through π0π0\pi^0 \pi^0 nuclear photoproduction

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    In order to assess the relevance of chiral dynamics in the scalar sector we address two recent problems: radiative decay of the ϕ\phi, for which there are quite recent data from Frascati, and the modification of the σ\sigma properties in the nuclear medium seen through the π0π0\pi^0 \pi^0 photoproduction in nuclei.Comment: Talk given at the High Energy Physics Workshop "Scalar Mesons: an Interesting Puzzle for QCD", Utica, New York, May 200

    Watson's theorem and the NΔ(1232)N\Delta(1232) axial transition

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    We present a new determination of the NΔN\Delta axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez {\it et al.} [Phys. Rev. D76, 033005 (2007)] is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger C5A(0)C_5^A(0), in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.Comment: 17 latex pages, 7 figures, 2 tables. Some typos correcte

    Years of sunlight exposure and cataract: a case-control study in a Mediterranean population.

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    BACKGROUND: We aimed to investigate the relation between sunlight exposure and risk of cataract. METHODS: We carried out a frequency-matched case-control study of 343 cases and 334 controls attending an ophthalmology outpatient clinic at a primary health-care center in a small town near Valencia, Spain. All cases were diagnosed as having a cataract in at least one eye based on the Lens Opacification Classification system (LOCS II). Controls had no opacities in either eye. All cases and controls were interviewed for information on outdoor exposure, "usual" diet, history of severe episodes of diarrhea illness, life-style factors and medical and socio-demographic variables. Blood antioxidant vitamin levels were also analyzed. We used logistic regression models to estimate sex and age-adjusted odds ratios (ORs) by quintiles of years of occupational outdoor exposure, adjusting for potential confounders such as smoking, alcohol consumption, serum antioxidants and education. RESULTS: No association was found between years of outdoor exposure and risk of cataract. However, exploratory analyses suggested a positive association between years of outdoor exposure at younger ages and risk of nuclear cataract later in life. CONCLUSION: Our study does not support an association with cataract and sunlight exposure over adult life

    Nuclear effects in neutrino induced reactions

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    We discuss the relevance of nuclear medium effects in the analysis of some low and medium energy neutrino reactions of current interest. In particular, we study the Quasi-Elastic (QE) process, where RPA correlations and Final State Interactions (FSI) are shown to play a crucial role. We have also investigated the neutrino induced coherent pion production. We find a strong reduction of the cross section due to the distortion of the pion wave function and the modification of the production mechanisms in the nucleus. The sensitivity of the results to the axial NΔN\Delta coupling C5A(0)C_5^A(0) has been also investigated.Comment: To appear in the proceedings of Chiral Symmetry in Hadron and Nuclear Physics (Chiral07), Osaka, Japan, November 13-16, 200

    Coleta de dados em campo com auxílio de dispositivos móveis Android.

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    Este Comunicado Técnico visa apresentar os passos necessários para a utilização do programa GeoPaparazzi no campo, incluindo a instalação e o funcionamento do programa, a geração de mapas base personalizados, a configuração de formulários de coleta de dados e a exportação dos dados coletados. Pressupõe-se que o leitor tenha domínio de algumas operações, como procedimentos para copiar dados do computador pessoal para o dispositivo móvel e vice-versa, gerar mapas base ou mosaicos georreferenciados e utilizar programas via linha de comando no computador pessoal.bitstream/item/99818/1/CT-34.pd

    DYNAMIC RELATIONSHIPS: E-COMMERCE SALES AND KEY EXOGENOUS VARIABLES IN THE PHILIPPINES

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    This study delves into the complex and evolving landscape of e-commerce in the Philippines, focusing on the relationship between E-Commerce Sales as the endogenous variable and a set of influential exogenous variables, including Digital Marketing Spending, GDP Growth, Internet Penetration, and Mobile Phone Ownership. This research employs a flexible spline modeling approach, uncovers non-linear associations, and offers significant implications for academic understanding and practical applications. The findings underscore the growing impact of Digital Marketing Spending on E-Commerce Sales, revealing the paramount role of online advertising and promotional strategies in the digital marketplace. Moreover, the study explains the intricate interplay between GDP Growth, Internet Penetration, Mobile Phone Ownership, and E-Commerce Sales, highlighting the non-linear nature of these relationships. As the Philippines continues its economic expansion and technological integration, these associations exhibit insightful implications for policymakers, businesses, and e-commerce stakeholders.  Article visualizations
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