Light hadron spectroscopy with $O\left(a\right)\mathrm{}$ improved dynamical fermions

We present the first results for the static quark potential and the light hadron spectrum using dynamical fermions at $\beta =5.2\mathrm{}$ using an $O\left(a\right)\mathrm{}$ 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, $m_{\mathrm{PS}}{/m}_V,$ varies from 0.86 to 0.67. Finite-size effects are studied by using three different volumes $8^3\times 24,$ ${12}^3\times 24,$ and ${16}^3\times 24.$ 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.