Multi-jet event rates in deep inelastic scattering and determination of the strong coupling constant

Abstract

Jet event rates in deep inelastic ep scattering at HERA are investigated applying the modified JADE jet algorithm. The data are corrected for detector and hadronization effects and then compared with perturbative QCD predictions using next-to-leading order calculations. The strong coupling constant $\alpha_s (M^2_Z)$ is determined evaluating the jet event rates. Values of $\alpha_s (Q^2)$ are extracted in four different bins of the negative squared momentum transfer $Q^2$ in the range from 40 GeV $^2$ to 4000 GeV $^2$ . A combined fit of the renormalization group equation to these several $\alpha_s (Q^2)$ values results in $\alpha_s (M^2_Z) = 0.117 \pm 0.003 (stat)^{+0.009}_{0.013} (sys) + 0.006 (jet algorithm)$