A. Ukawa

Hadron scattering lengths in lattice QCD

Lattice QCD calculation of s-wave hadron scattering lengths in the channels pi-pi, pi-N, K-N, {bar K}-N and N-N is carried out in the quenched QCD at

Pion-Nucleon Sigma Term in Lattice QCD

beta=6/g^2=5.7

Fate of the critical line and chiral transition in finite-temperature lattice QCD with the Wilson quark action

. A variant of the method of wall sourceis developed for this purpose, which reduces the computer time by a factor L^3 on an L^3xT lattice compared to the conventional point source method and avoids the Fierz mixing problem. A version of the method in which gauge configurations are not fixed to any gauge can be extended to calculate disconnected quark loop con- tributions in hadron two- and three-point functions. An analytical estimate of statistical errors for this method is worked out, and the magnitude of errors without and with gauge fixing is compared for the case of pi-pi four-point functions calculated with the KS quark action. For pi-pi scattering both I=0 and 2 scattering lengths are evaluated using the KS and Wilson quark actions on a 12^3x20 lattice. For the same size of lattice, pi-N, K-N and {bar K}-N scattering lenghts are calculated with the Wilson quark action. For the pi-pi and pi-N cases simulation results are consistent with the predictions of current algebra and PCAC within one to two standard deviations up to quite heavy quark masses corresponding to

Heavy-light matrix elements with the Wilson quark action

m_pi/m_rhoapprox 0.74

Analysis of hadron propagators with one thousand configurations on a 24[3] × 64 lattice at β = 6.0

, while for the K-N and {bar K}-N cases the agreement is within a factor of two. For N-N scat- tering simulations with the Wilson action on a 20^4 lattice with heavy quarks with

Status of the CP-PACS project

m_pi/m_rhoapprox 0.74-0.95

Charmonium spectroscopy with heavy Kogut-Susskind quarks

, where the deuteron is expected to become unbound from a phenomenological study with one-boson exchange potentials, show that the nucleon-nucleon force is attractive for both spin triplet and singlet channels, and that the scattering lengths are substantially larger compared to those for the pi-pi and pi-N cases even for such heavy quarks.

Scalar and axial vector matrix elements of proton in quenched QCD: Calculation of both connected and disconnected contributions

We calculate both connected and disconnected contribution to the �-N �-term in quenched lattice QCD with Wilson quark action on a 12 3 × 20 lattice at � = 5.7. The latter is evaluated with the aid of the variant wall source method, which was previously applied successfully for extraction of �-� scattering lengths and � ′ meson mass. We found that the disconnected contribution is about twice larger than the connected one. The value for � ¯ �

Sea quark effects on the strong coupling constant

Finite-temperature phase structure of lattice QCD with the Wilson quark action is analyzed. We show that the critical line at finite temperatures, defined to be the line of vanishing pion screening mass, turns back toward strong coupling, forming a cusp on the (β,K) plane, and that the line of thermal transition runs past the tip of the cusp without touching the critical line. Previous results are discussed in the light of our findings.

eta-prime meson mass in lattice QCD.

Status report is made of our quenched study of heavy-light matrix elements employing the Wilson quark action for heavy quark. Results obtained up to now with 200 configurations at β = 6.1 on a 24 3 × 64 lattice and with 100 configurations at β = 6.3 on a 32 3 × 80 lattice suggest that the pseudoscalar decay constant varies little over this range of β in both charm and bottom regions. Results for the B parameter are also reported.