Electron-Positron Annihilation into Four Jets at Next-to-Leading Order in $α_s$

We calculate the rate for $e^+e^-$ annihilation into four jets at next-to-leading order in perturbative QCD, but omitting terms that are suppressed by one or more powers of $1/\Nc^2$, where $\Nc$ is the number of colors. The $\cO(\alpha_s^3)$ corrections depend strongly on the jet resolution parameter $\ycut$ and on the clustering and recombination schemes, and they substantially improve the agreement between theory and data.