Measurement of fermion pair production in $e^{+}e^{-}$ annihilation and interpretation in terms of new physics phenomena

Preliminary hadronic and leptonic cross sections and leptonic asymmetry measurements made with the ALEPH detector in e+e- collisions at 161 GeV and 172 GeV are reported. The data samples correspond to integrated luminosities of 11.08 pb-1 at 161 GeV and 10.65 pb-1 at 172 GeV. Results are given includingand excluding the radiative gamma Z0 contribution. The measurements agree well with Standard Model expectations. They are interpreted in terms of four fermion contact interactions, with limits upon the energy scale of such processes being derived under various hypotheses. Limits are a placed on the t-channel exchange of new heavy scalar particles, such as leptoquarks or squarks with R-parity violation.