649 research outputs found

    Hadronic Decays of Excited Heavy Mesons

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    We studied the hadronic decays of excited states of heavy mesons (D, D_s, B and B_s) to lighter states by emission of pi, eta or K. Wavefunctions and energy levels of these excited states are determined using a Dirac equation for the light quark in the potential generated by the heavy quark (including first order corrections in the heavy quark expansion). Transition amplitudes are computed in the context of the Heavy Chiral Quark Model.Comment: 4 pages (incl. figures), proceedings of the IV International Conference on "Hyperons, Charm and Beauty Hadrons", Valencia (Spain

    RPA quasi-elastic responses in infinite and finite nuclear systems

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    Quasi-elastic responses in nuclear matter and in 12^{12}C and 40^{40}Ca nuclei are calculated in ring approximation to investigate the finite size effects on the electromagnetic quasi-elastic responses. A method to simulate these effects in infinite systems calculations is proposed. The sensitivity of the results to the various terms of the residual interaction is studied. The results of nuclear matter RPA calculations are compared with those obtained in ring approximation to evidence the importance of the exchange terms.Comment: 14 pages, 8 figure

    Pelletized Forage-Based Rations as Alternative Feeds for Improving Goat Productivity

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    Goat farming is very popular in the Philippines as it is considered by many to be a viable rural enterprise. Despite this, the goat industry is faced with many challenges, including problems relating to high pre-weaning mortality, poor nutrition and lack of strategic approaches to accelerate genetic improvement. The long term rate of increase of goat numbers is only 0.97% per annum, due to high offtake rates and low productivity. Thus, the Philippine goat population is only expected to reach 4.27million by 2020 (compared with the target of 6.2 million), given the 3.88million population in 2010 (Alo 2012). Interventions are needed to accelerate growth of the goat population. Goats are typically fed on locally available resources which are characterised by low quality and highly variable availability. These characteristics can be overcome through processing techniques such as sun drying and pelleting to ensure year round feed supply. Pelleting offers particular advantages. Feeding animals with pellets provides better feed efficiency, greater starch digestibility, less feed waste, non-selective feeding, better handling and storage, and increased income due to more efficient feeding and higher productivity. While pellets are available for swine, poultry and buffalo in the Philippine market, pellets for goats are not currently available. The aim of this study was to develop pelletized forage-based rations for goats and evaluate them for their technical and financial viability

    Neutrino-Oxygen CC0π\pi scattering in the SuSAv2-MEC model

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    We present the predictions of the SuSAv2-MEC model for the double differential charged-current muonic neutrino (antineutrino) cross section on water for the T2K neutrino (antineutrino) beam. We validate our model by comparing with the available inclusive electron scattering data on oxygen and compare our predictions with the recent T2K νμ\nu_\mu-16^{16}O data, finding good agreement at all kinematics. We show that the results are very similar to those obtained for νμ12\nu_\mu-^{12}C scattering, except at low energies, and we comment on the origin of this difference. A factorized spectral function model of 16^{16}O is also included for purposes of comparison.Comment: 28 pages, 10 figures, JLAB-THY-17-2586. Version 2 accepted for publication in Journal of Physics G: Nucl. Part. Phy

    Exchange Current Corrections to Neutrino--Nucleus Scattering

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    Relativistic exchange current corrections to neutrino--nucleus cross sections are presented assuming non--vanishing strange quark form factors for the constituent nucleons. For charged current processes the exchange current corrections can lower the impulse approximation results by 10\% while these corrections are found to be sensitive to both the nuclear density and the strange quark axial form factor of the nucleon for neutral current processes. Implications on the LSND experiment to determine this form factor are discussed.Comment: 11 pages, 2 figures, revtex 3.0, full postscript version of the file and figures available at http://www.nikhefk.nikhef.nl/projects/Theory/preprints/preprints.html To appear in Phys. Rev. Lett

    Deuteron Magnetic and Quadrupole Moments with a Poincar\'e Covariant Current Operator in the Front-Form Dynamics

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    The deuteron magnetic and quadrupole moments are unambiguosly determined within the front-form Hamiltonian dynamics, by using a new current operator which fulfills Poincar\'e, parity and time reversal covariance, together with hermiticity and the continuity equation. For both quantities the usual disagreement between theoretical and experimental results is largely removed.Comment: To appear in Phys. Rev. Let

    Two-nucleon knockout contributions to the 12^{12}C(e,ep)(e,e'p) reaction in the dip and {Δ\Delta}(1232) regions

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    The contributions from 12^{12}C(e,epn)(e,e'pn) and 12^{12}C(e,epp)(e,e'pp) to the semi-exclusive 12^{12}C(e,ep)(e,e'p) cross section have been calculated in an unfactorized model for two-nucleon emission. We assume direct two-nucleon knockout after virtual photon coupling with the two-body pion-exchange currents in the target nucleus. Results are presented at several kinematical conditions in the dip and Δ\Delta(1232) regions. The calculated two-nucleon knockout strength is observed to account for a large fraction of the measured (e,ep)(e,e'p) strength above the two-nucleon emission threshold.Comment: 12 Revtex pages, 4 postscript figures (available upon request), University of Gent preprint SSF94-02-0

    Mean-field calculations of quasi-elastic responses in 4He

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    We present calculations of the quasi-elastic responses functions in 4He based upon a mean-field model used to perform analogous calculations in heavier nuclei. The meson exchange current contribution is small if compared with the results of calculations where short-range correlations are explicitly considered. It is argued that the presence of these correlations in the description of the nuclear wave functions is crucial to make meson exchange current effects appreciable.Comment: uuencoded file containing 7 LaTex peges plus 3 ps figures. To be published in Physical Review

    Experimental and Theoretical Results for Weak Charge Current Backward Proton Production

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    In this paper, we do three things in the study of deuteron break-up by high energy neutrino beams. (1) We present previously unpublished data on neutrino induced backward protons from deuteron targets; (2) we calculate the contributions from both the two-nucleon (2N) and six-quark (6q) deuteron components, which depend upon the overall normalization of the part that is 6q; and (3) we suggest other signatures for distinguishing the 2N and 6q clusters. We conclude that the 6q cluster easily explains the shape of the high momentum backward proton spectrum, and its size is nicely explained if the amount of 6q is one or a few percent by normalization of the deuteron. There is a crossover, above which the 6q contribution is important or dominant, at 300--400 MeV/c backward proton momentum.Comment: 8 pages, 5 figure
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