611 research outputs found

    Two-Nucleon Bound States in Quenched Lattice QCD

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    We address the issue of bound state in the two-nucleon system in lattice QCD. Our study is made in the quenched approximation at the lattice spacing of a = 0.128 fm with a heavy quark mass corresponding to m_pi = 0.8 GeV. To distinguish a bound state from an attractive scattering state, we investigate the volume dependence of the energy difference between the ground state and the free two-nucleon state by changing the spatial extent of the lattice from 3.1 fm to 12.3 fm. A finite energy difference left in the infinite spatial volume limit leads us to the conclusion that the measured ground states for not only spin triplet but also singlet channels are bounded. Furthermore the existence of the bound state is confirmed by investigating the properties of the energy for the first excited state obtained by 2x2 diagonalization method. The scattering lengths for both channels are evaluated by applying the finite volume formula derived by Luscher to the energy of the first excited states.Comment: 34 pages, 28 figure

    Finite-Temperature Phase Structure of Lattice QCD with the Wilson Quark Action for Two and Four Flavors

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    We present further analyses of the finite-temperature phase structure of lattice QCD with the Wilson quark action based on spontaneous breakdown of parity-flavor symmetry. Results are reported on (i) an explicit demonstration of spontaneous breakdown of parity-flavor symmetry beyond the critical line, (ii) phase structure and order of chiral transition for the case of Nf=4N_f=4 flavors, and (iii) approach toward the continuum limit.Comment: Poster presented at LATTICE96(finite temperature); 4 pages, Latex, uses espcrc2 and epsf, seven ps figures include

    An Exploratory Study of Nucleon-Nucleon Scattering Lengths in Lattice QCD

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    An exploratory study is made of the nucleon-nucleon ss-wave scattering lengths in quenched lattice QCD with the Wilson quark action. The π\pi-NN and π\pi-π\pi scattering lengths are also calculated for comparison. The calculations are made with heavy quarks corresponding to mπ/mρ0.730.95m_\pi/m_\rho\approx 0.73-0.95. The results show that the NN-NN system has an attractive force in both spin-singlet and triplet channels, with their scattering lengths significantly larger than those for the π\pi-NN and π\pi-π\pi cases, a trend which is qualitatively consistent with the experiment. Problems toward a more realistic calculation for light quarks are discussed.Comment: 9 pages. Latex file. Figures are also included as ps file