Isospin Splitting in the Pion-Nucleon Couplings from QCD Sum Rules

We use QCD sum rules for the three point function of a pseudoscalar and two nucleonic currents in order to estimate the charge dependence of the pion nucleon coupling constant coming from isospin violation in the strong interaction. The effect can be attributed primarily to the difference of the quark condensates and . Assuming that the pi0 is a pure isostate we obtain for the splitting between the coupling of proton and neutron to the neutral pion an interval of [0.008 ; 0.023], the uncertainties coming mainly from the input parameters. In order to obtain the coupling to a physical pi0 we have to take pi - eta mixing into account leading to an interval of [0.012 ; 0.037]. The charged pion nucleon coupling is found to be the average of the two neutral ones. Electromagnetic effects are not included.Comment: contributed talk at CIPANP97 (Big Sky, Montana); 3 pages (aipproc.sty), no figure

T-Duality and Two-Loop Renormalization Flows

Manifest T-duality covariance of the one-loop renormalization group flows is shown for a generic bosonic sigma model with an abelian isometry, by referring a set of previously derived consistency conditions to the tangent space of the target. For a restricted background, T-duality transformations are then studied at the next order, and the ensuing consistency conditions are found to be satisfied by the two-loop Weyl anomaly coefficients of the model. This represents an extremely non-trivial test of the covariance of renormalization group flows under T-duality, and a stronger condition than T-duality invariance of the string background effective action.Comment: 18 pp., plain TeX + harvmac. Typos in Eqs. (4.3), (4.5) and (4.7) corrected, and references adde

Isospin dependence of the three-nucleon force

We classify $A$--nucleon forces according to their isospin dependence and discuss the most general isospin structure of the three--nucleon force. We derive the leading and subleading isospin--breaking corrections to the three--nucleon force using the framework of chiral effective field theory.Comment: 21 pages, 6 figure

Mamoeiro transgênico no Brasil: resultados obtidos e legislação para sua liberação.

No Brasil, em março de 2005, a Lei nº 11.105 entre outras medidas, estabeleceu as normas de segurança e mecanismos de fiscalização de atividades que envolvam organismos geneticamente modificados (OGM) e seus derivados, criou o Conselho Nacional de Biossegurança (CNBS), reestruturou a Comissão Técnica Nacional de Biossegurança (CTNBio), dispôs sobre a Política Nacional de Biossegurança (PNB) e revogou a Lei de biossegurança anterior, a Lei Nº 8.974 (CTNBio, 2011)

Indexação de plantas para viroses.

No mundo há milhares de viroses descritas, cada uma possuindo uma específica gama de hospedeiros. A sintomatologia produzida varia bastante, dependendo do vírus ou da estirpe presente, da planta infectada e das condições do ambiente. No Brasil, em fruteiras tropicais, citros e mandioca já se constatou a ocorrência de várias viroses, como o vírus associado com a murcha do abacaxi, o vírus das estrias da bananeira, o vírus da meleira do mamoeiro, o vírus da tristeza dos citros e o vírus do mosaico das nervuras da mandioca. Na natureza, a maioria das viroses são transmitidas por insetos, mas também é comum sua transmissão por sementes, manivas ou enxertos obtidos de plantas infectadas. As ferramentas de corte contaminadas também podem propiciar a disseminação de algumas viroses.bitstream/item/25859/1/http-agrosoft.comID27016-pdf.pdfDisponível em : Acesso em : 24 jan. 2011

Viroses da bananeira.

A cultura da bananeira pode ser infectada por diversas viroses, como o vírus do topo em leque da bananeira, o vírus das estrias da bananeira, o vírus do mosaico do pepino, o vírus do mosaico das brácteas da bananeira, o Banana mild mosaic virus, o Banana virus X, o Abaca bunchy top virus e o Sugarcane mosaic virus. No Brasil, até o momento foram relatados o vírus do mosaico do pepino e o vírus das estrias da bananeira.bitstream/item/25824/1/Meissner-agrosoft.com-pdf.pdfDisponível em: Acesso em: 20 jan. 2011

Nuclear Forces and Few-Nucleon Studies Based on Chiral Perturbation Theory

After a brief review on the status of few--nucleon studies based on conventional nuclear forces, we sketch the concepts of the effective field theory approach constrained by chiral symmetry and its application to nuclear forces. Then first results for few--nucleon observables are discussed.Comment: 8 pages, presented by W. Gloeckle at the International Symposium on "A New Era of Nuclear Structure Physics", Kurokawa Village (Niigata Pref.), Japan, Nov. 19-22, 200

Few-Nucleon Systems with Two-Nucleon Forces from Chiral Effective Field Theory

Nucleon-nucleon (NN) forces from chiral perturbation theory at next-to-leading (NLO) and next-to-next-to-leading order (NNLO) are applied to systems with two, three and four nucleons. At NNLO, we consider two versions of the chiral potential which differ in the strength of the two-pion-exchange (TPE) but describe two nucleon observables equally well. The NNLO potential leads to unphysical deeply bound states in the low partial waves and effects of the 3N forces, which appear first at this order, are expected to be large. We provide arguments for a reduction of the TPE potential and introduce the NNLO* version of the NN forces. We calculate nd scattering observables as well as various properties of 3H and 4He with the NNLO* potential and find good agreement with the data and with predictions based upon the standard high-precision potentials. We find an improved description of the 3H and 4He binding energies.Comment: 34 pages, 25 figure