NLO QCD corrections to five-jet production at LEP and the extraction of alpha_s(M_Z)

TL;DR

This paper calculates NLO QCD corrections for five-jet production in e+e- collisions at LEP, compares results with data, and extracts a value for alpha_s(M_Z) with improved precision.

Contribution

It provides the first NLO QCD corrections for five-jet production at LEP and demonstrates a method to extract alpha_s(M_Z) from high-multiplicity jet data.

Findings

NLO corrections improve theoretical predictions for five-jet observables.

A competitive value of alpha_s(M_Z) = 0.1156 was extracted from LEP data.

Hadronization effects were estimated using SHERPA with CKKW merging.

Abstract

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 alpha_s(M_Z) = 0.1156 +0.0041 -0.0034 can be extracted from the distribution of the five-jet resolution parameter and the five-jet rate at LEP1 and LEP2.