952 research outputs found

    On the estimate of the sigma^(I = 1)_(KN)(0)-term value from the energy level shift of kaonic hydrogen in the ground state

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    Using the experimental data on the energy level shift of kaonic hydrogen in the ground state (the DEAR Collaboration, Phys. Rev. Lett. 94, 212302 (2005)) and the theoretical value of the energy level shift, calculated within the phenomenological quantum field theoretic approach to the description of strong low-energy anti-K N and anti-K NN interactions developed at Stefan Meyer Institut fuer subatomare Physik in Vienna, we estimate the value of the sigma^(I = 1)_(KN)(0)-term of low-energy anti-K N scattering. We get sigma^(I = 1)_(KN)(0) = (433 +/- 85) MeV. This testifies the absence of strange quarks in the proton structure.Comment: 7 pages, no figure

    Análise cienciométrica de espaços verdes urbanos e seus serviços ecossistêmicos.

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    O acelerado crescimento populacional e urbano nas últimas décadas intensificou a necessidade de pesquisas sobre o ecossistema urbano e os serviços por ele oferecidos, visando ao bem-estar da população urbana por meio da conservação da natureza. O reconhecimento dos serviços ecossistêmicos fornecidos pelos Espaços Verdes Urbanos (EVUs) pode subsidiar a tomada de decisão para que as cidades promovam o desenvolvimento sustentável, conservando e/ou restaurando os serviços ecossistêmicos e a biodiversidade, para que a vida das pessoas nas cidades seja viável diante dos desafios impostos pelas mudanças climáticas. Este artigo tem por objetivo principal avaliar como os serviços ecossistêmicos fornecidos pelos EVUs estão sendo abordados no meio científico. Realizou-se um levantamento cienciométrico e, posteriormente, uma análise bibliográfica dos principais artigos para avaliar o conhecimento científico atual, as principais limitações teóricas e as lacunas e oportunidades para avanços no conhecimento sobre o tema. Os resultados apontam que as pesquisas dos serviços ecossistêmicos em EVUs foram intensificadas a partir de 2005 e apresentaram uma taxa exponencial de crescimento de 30% ao ano, particularmente nos países mais desenvolvidos. A análise bibliográfica aponta que os serviços ecossistêmicos reguladores e culturais no contexto urbano são aqueles de maior importância, e que são necessárias novas metodologias para avaliar e eventualmente precificar esses serviços

    Chiral unitary approach to the K^- deuteron scattering length

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    Starting from a recent model where the Kbar N amplitudes are evaluated from the chiral Lagrangians using a coupled channel unitary method, we evaluate here the scattering length for K^- deuteron scattering. We find that the double scattering contribution is very large compared to the impulse approximation and that the charge exchange contribution of this rescattering is as large as the sequential K^- scattering on the two nucleons. Higher order rescattering corrections are evaluated using coupled channels with K^- and Kbar^0 within the integral form of the fixed centre approximation to the Faddeev equations. The higher order corrections involving intermediate pions and hyperons are found negligible.Comment: 16 pages, 4 figures, revised version to appear in Nucl. Phys.

    VIP: An Experiment to Search for a Violation of the Pauli Exclusion Principle

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    The Pauli Exclusion Principle is a basic principle of Quantum Mechanics, and its validity has never been seriously challenged. However, given its fundamental standing, it is very important to check it as thoroughly as possible. Here we describe the VIP (VIolation of the Pauli exclusion principle) experiment, an improved version of the Ramberg and Snow experiment (E. Ramberg and G. Snow, {\it Phys. Lett. B} {\bf 238}, 438 (1990)); VIP has just completed the installation at the Gran Sasso underground laboratory, and aims to test the Pauli Exclusion Principle for electrons with unprecedented accuracy, down to β2/2≈10−30−10−31\beta^2/2 \approx 10^{-30} - 10^{-31}. We report preliminary experimental results and briefly discuss some of the implications of a possible violation.Comment: Plenary talk presented by E. Milotti at Meson 2006, Cracow, 9-13 June 200

    Search for Deeply Bound Kaonic Nuclear States with AMADEUS

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    We briefly report on the search for Deeply Bound Kaonic Nuclear States with AMADEUS in the Sigma0 p channel following K- absorption on 12C and outline future perspectives for this work

    New experimental limit on Pauli Exclusion Principle violation by electrons (the VIP experiment)

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    The Pauli Exclusion Principle is one of the basic principles of modern physics and is at the very basis of our understanding of matter: thus it is fundamental importance to test the limits of its validity. Here we present the VIP (Violation of the Pauli Exclusion Principle) experiment, where we search for anomalous X-rays emitted by copper atoms in a conductor: any detection of these anomalous X-rays would mark a Pauli-forbidden transition. ] VIP is currently taking data at the Gran Sasso underground laboratories, and its scientific goal is to improve by at least four orders of magnitude the previous limit on the probability of Pauli violating transitions, bringing it into the 10**-29 - 10**-30 region. First experimental results, together with future plans, are presented.Comment: To appear in proceedings of the XLVI International Winter Meeting on Nuclear Physics, Bormio, Italy, January 20-26, 200

    The VIP Experiment

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    The Pauli Exclusion Principle (PEP) is a basic principle of Quantum Mechanics, and its validity has never been seriously challenged. However, given its importance, it is very important to check it as thoroughly as possible. Here we describe the VIP (Violation of PEP) experiment, an improved version of the Ramberg and Snow experiment (Ramberg and Snow, Phys. Lett. B238 (1990) 438); VIP shall be performed at the Gran Sasso underground laboratories, and aims to test the Pauli Exclusion Principle for electrons with unprecedented accuracy, down to β22∼10−30\frac{\beta^2}{2} \sim 10^{-30}Comment: 7 pages, 5 figures, PDF only, presented by Edoardo Milotti to the conference "Quantum Theory: reconsideration of foundations-3", Vaxjo (Sweden), June, 6-11 200
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