First results from the asymmetric O(a) improved Fermilab action

We present first results from calculations using an O(a) improved (FNAL) sp ace-time asymmetric fermion action on a 12(3) x 24 quenched lattice at beta = 5.7 and with c(SW) = 1.57. The mass dependent asymmetry parameter zeta i s determined non-perturbatively from the energy-momentum dispersion relatio n. Calculations have been made in the charm and bottom quark mass sectors i n order to test the zeta dependence of the spectrum, since it is at these h eavier masses that the asymmetry is expected to be most relevant.