NLO QCD corrections to five-jet production at LEP and the extraction of α s (M Z )

The highest exclusive jet multiplicity studied at LEP experiments is five. In this paper we compute the next-to-leading order QCD corrections to e + e − annihilation to five jets, essentially closing the (pure) perturbative QCD studies of exclusive jetty final states at LEP. We compare fixed-order perturbative results with ALEPH data. We estimate hadronization corrections to five-jet observables using the event generator SHERPA, which employs the CKKW procedure to combine a reliable perturbative treatment of high-multiplicity jet final states with parton showers. We show that a competitive value of the strong coupling constant αₛ( MZ ) = 0.1156- 0.0034+ 0.0041 can be extracted from the distribution of the five-jet resolution parameter and the five-jet rate at LEP1 and LEP2.