The minimal set of electroweak precision parameters

Abstract

We present a simple method for analyzing the impact of precision electroweak data above and below the $Z$ peak on flavor-conserving, heavy new physics. We find that experiments have probed about ten combinations of new-physics effects, which to a good approximation can be condensed into the effective oblique parameters $\stackrel{^}{S}$, $\stackrel{^}{T}$, $\stackrel{^}{U}$, $V$, $X$, $W$, $Y$ (we prove positivity constraints $W,Y\ensuremath{\ge}0$) and three combinations of quark couplings (including a distinct parameter for the bottom). We apply our method to generic extra ${Z}^{\ensuremath{'}}$ vectors.