Energy dependence of nucleon-nucleon potentials

We investigate the energy dependence of potentials defined through the Bethe-Salpeter wave functions. We analytically evaluate such a potential in the Ising field theory in 2 dimensions and show that its energy dependence is weak at low energy. We then numerically calculate the nucleon-nucleon potential at non-zero energy using quenched QCD with anti-periodic boundary condition. In this case we also observe that the potentials are almost identical at $E\simeq 0$ and $E\simeq 50$ MeV, where $E$ is the center of mass kinetic energy.Comment: 7 pages, 5 figures, talk presented at the XXVI International Symposium on Lattice Field Theory, July 14-19, 2008, Williamsburg, Virginia, US

Hyperon–nucleon force from lattice QCD

We calculate potentials between a proton and a Ξ0 (hyperon with strangeness −2) through the equal-time Bethe–Salpeter wave function, employing quenched lattice QCD simulations with the plaquette gauge action and the Wilson quark action on (4.5 fm)4 lattice at the lattice spacing asimilar, equals0.14 fm. The ud quark mass in our study corresponds to mπsimilar, equals0.37 and 0.51 GeV, while the s quark mass corresponds to the physical value of mK. The central pΞ0 potential has a strong (weak) repulsive core in the View the MathML source (View the MathML source) channel for rless, approximate0.6 fm, while the potential has attractive well at medium and long distances (0.6 fmless, approximaterless, approximate1.2 fm) in both channels. The sign of the pΞ0 scattering length and its quark mass dependence indicate a net attraction in both channels at low energies

Baryon-Baryon Interactions in the Flavor SU(3) Limit from Full QCD Simulations on the Lattice

We investigate baryon-baryon (BB) interactions in the 3-flavor full QCD simulations with degenerate quark masses for all flavors. The BB potentials in the orbital S-wave are extracted from the Nambu-Bethe-Salpeter wave functions measured on the lattice. We observe strong flavor-spin dependences of the BB potentials at short distances. In particular, a strong repulsive core exists in the flavor-octet and spin-singlet channel (the 8_s representation), while an attractive core appears in the flavor singlet channel (the 1 representation). We discuss a relation of such flavor-spin dependence with the Pauli exclusion principle in the quark level. Possible existence of an H-dibaryon resonance above the Lambda-Lambda threshold is also discussed.Comment: 16 pages, 4 figures, ptptex.cls use