19,474 research outputs found

    Full QED+QCD Low-Energy Constants through Reweighting

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    The effect of sea quark electromagnetic charge on meson masses is investigated, and first results for full QED+QCD low-energy constants are presented. The electromagnetic charge for sea quarks is incorporated in quenched QED+full QCD lattice simulations by a reweighting method. The reweighting factor, which connects quenched and unquenched QED, is estimated using a stochastic method on 2+1 flavor dynamical domain-wall quark ensembles.Comment: 5 pages, 9 figures, REVTeX 4.1, v2: published versio

    Coordinate space proton-deuteron scattering calculations including Coulomb force effects

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    We present a practical method to solve the proton-deuteron scattering problem at energies above the three-body breakup threshold, in which we treat three-body integral equations in coordinate space accommodating long-range proton-proton Coulomb interactions. The method is examined for phase shift parameters, and then applied to calculations of differential cross sections in elastic and breakup reactions, analyzing powers, etc. with a realistic nucleon-nucleon force and three-nucleon forces. Effects of the Coulomb force and the three-nucleon forces on these observables are discussed in comparing with experimental data.Comment: 15 pages, 14 figures, submitted to PR

    The square-lattice spiral magnet Ba_2CuGe_2O_7 in an in-plane magnetic field

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    The magnetic structure of Ba_2CuGe_2O_7 is investigated by neutron diffraction in magnetic fields applied along several directions in the (a,b)(a,b) plane of the crystal. In relatively weak fields, H0.5H\lesssim 0.5~T, the propagation vector of the spin-spiral rotates to form a finite angle with the field direction. This angle depends on the orientation of HH itself. The rotation of the propagation vector is accompanied by a re-orientation of the plane of spin rotation in the spiral. The observed behaviour is well described by a continuous-limit form of a free energy functional that includes exchange and Dzyaloshinskii-Moriya interactions, as well as the Zeeman energy and an empirical anisotropy term.Comment: 7 pages, 6 figure

    Neutrino Oscillations in Intermediate States.II -- Wave Packets

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    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=3×102\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 101310^{-13} m for 0.4 MeV neutrino.Comment: 29 pages, 11 figures. typos corrected, appendix adde

    Central and tensor components of three-nucleon forces in low-energy proton-deuteron scattering

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    Contributions of three-nucleon forces (3NF) to proton-deuteron scattering observables at energies below the deuteron breakup threshold are studied by solving the Faddeev equation that includes the Coulomb interaction. At E_p=3.0 MeV, we find that the central part of a two-pion exchange 3NF removes the discrepancy between measured cross sections and the calculated ones by two-nucleon forces, and improves the agreement with T_{22} experimental data. However, the tensor part of the 3NF fails in reproducing data of the analyzing power T_{21} by giving worse agreement between the measured and the calculated. Detailed examinations of scattering amplitudes suggest that a P-wave contribution in spin quartet tensor amplitudes has unsuitable sign for reproducing the T_{21} data.Comment: 6 pages, 6 figure