Light hadron spectroscopy with O(a) improved dynamical fermions

We present the first results for the static quark potential and the light hadron spectrum using dynamical fermions at b55.2 using an O(a) improved Wilson fermion action together with the standard Wilson plaquette action for the gauge part. Sea quark masses were chosen such that the pseudoscalar-vector mass ratio, mPS /mV , varies from 0.86 to 0.67. Finite-size effects are studied by using three different volumes 83324, 123324, and 163324. Comparing our results to previous ones obtained using the quenched approximation, we find evidence for sea quark effects in quantities such as the static quark potential and vector-pseudoscalar hyperfine splitting. (@S0556-2821(99)00613-X)