I=2 pion scattering phase shift with Wilson fermions

We present a lattice QCD calculation of the scattering phase shift for the I52 S-wave two-pion system using the finite size method proposed by Luscher. We work in the quenched approximation employing the standard plaquette action at b55.9 for gluons and the Wilson fermion action for quarks. The phase shift is extracted from the energy eigenvalues of the two-pion system, which are obtained by a diagonalization of the pion four-point function evaluated for a set of relative spatial momenta. In order to change the momentum of the two-pion system, calculations are carried out on 24 3 360, 32 3 360, and 48 3 360 lattices. The phase shift is successfully calculated over the momentum range 0, p 2 ,0.3 GeV 2 .