15,726 research outputs found

    A Feynman graph selection tool in GRACE system

    Get PDF
    We present a Feynman graph selection tool {\tt grcsel}, which is an interpreter written in C language. In the framework of {\tt GRACE}, it enables us to get a subset of Feynman graphs according to given conditions.Comment: 3 pages, 2 figures, Latex, ACAT200

    Neutrino Oscillations in Intermediate States.II -- Wave Packets

    Full text link
    We analyze oscillations of intermediate neutrinos in terms of the scattering of particles described by Gaussian wave packets. We study a scalar model as in a previous paper (I) but in realistic situations, where the two particles of the initial state and final state are wave packets and neutrinos are in the intermediate state. The oscillation of the intermediate neutrino is found from the time evolution of the total transition probability between the initial state and final state. The effect of a finite lifetime and a finite relaxation time are also studied. We find that the oscillation pattern depends on the magnitude of wave packet sizes of particles in the initial state and final state and the lifetime of the initial particle. For Δm212=3×10−2\Delta m^2_{21}=3\times 10^{-2} eV2^2, the oscillation probability deviates from that of the standard formula if the wave packet sizes are around 10−1310^{-13} m for 0.4 MeV neutrino.Comment: 29 pages, 11 figures. typos corrected, appendix adde

    Operation of Faddeev-Kernel in Configuration Space

    Get PDF
    We present a practical method to solve Faddeev three-body equations at energies above three-body breakup threshold as integral equations in coordinate space. This is an extension of previously used method for bound states and scattering states below three-body breakup threshold energy. We show that breakup components in three-body reactions produce long-range effects on Faddeev integral kernels in coordinate space, and propose numerical procedures to treat these effects. Using these techniques, we solve Faddeev equations for neutron-deuteron scattering to compare with benchmark solutions.Comment: 20 pages, 8 figures, to be published in Few-Body System

    η\eta photoproduction off the deuteron and low-energy η\eta-nucleon interaction

    Full text link
    We study η\eta photoproduction off the deuteron (γd→ηpn\gamma d\to\eta pn) at a special kinematics: ∼0.94\sim 0.94 GeV of the photon beam energy and ∼0∘\sim 0^\circ of the scattering angle of the proton. This kinematics is ideal to extract the low-energy η\eta-nucleon scattering parameters such as aηNa_{\eta N} (scattering length) and rηNr_{\eta N} (effective range) because the η\eta-nucleon elastic scattering is significantly enhanced. We show that if a ratio RR, the γd→ηpn\gamma d\to\eta pn cross section divided by the γp→ηp\gamma p\to\eta p cross section convoluted with the proton momentum distribution in the deuteron, is measured with 5% error, Re[aηN]{\rm Re}[a_{\eta N}] (Re[rηN]{\rm Re}[r_{\eta N}]) can be determined at the precision of ∼±\sim\pm0.1 fm (∼±\sim\pm0.5 fm), significantly narrowing down the currently estimated range of the parameters. The measurement is ongoing at the Research Center for Electron Photon Science (ELPH), Tohoku University.Comment: 4 pages, 5 figures, Contribution to the Proceedings for 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japa
    • …
    corecore