Oblique electroweak corrections and new physics

Oblique electroweak parameters $\tilde{S}$, $\tilde{T}$, and $\tilde{U}$, defined so as to be nonvanishing only for physics beyond the standard model, are determined by direct use of high-statistics data from the CERN $e^{+}{e}^{-}$ collider LEP at different energy points around the $Z$ peak. Additional information from related electroweak measurements are used as constraints. The results are $\tilde{S}=-0.76\mathrm{}\pm 0.71$, $\tilde{T}=-0.70\mathrm{}\pm 0.49$, and $\tilde{U}=-0.11\mathrm{}\pm 1.07$. The consequent restrictions on extra fermion generations and an extra neutral gauge boson are discussed.