Operator dependence of hadron masses for Kogut-Susskind quarks on the lattice

Abstract

Operator dependence of hadron masses for the Kogut-Susskind fermion action is studied with a quenched simulation at β = 6.0 on a 24 3 × 40 lattice at the quark mass m q a = 0.01 and 0.02. With an improved wall source masses are extracted for all 64 meson and 120 baryon operators local in time. For mesons hadron masses are separated into two levels corresponding to π and ϱ. The results confirm the spin-flavor assignment in the literature. At a finer level, however, the spectrum shows some fine structure for π whereas a good degeneracy is observed for ϱ. The spectrum of baryons is also basically divided into the nucleon and Δ. However, one set of operators theoretically assigned to the nucleon in fact couples to Δ. We also find a substantial operator dependence in the nucleon mass. This gives rise to a large uncertainty in m N m ϱ depending on which operators are used to extract hadron masses. A brief discussion is also made for the characteristic of the opposite parity states.