2004/10/25 by The DELPHI Collaboration, J. Abdallah · 2 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1140/epjc/s2004-02060-7
published as Eur.Phys.J.C38:413-426,2005 · 29 pages, 14 figures, Accepted by Eur. Phys. J. C
arxiv created 2004/10/25 · openalex publication_date 2004/12/06 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/03
Hadronic events from the data collected with the DELPHI detector at LEP within the energy range from 89 GeV to 209 GeV are selected, their jet rates are determined and compared to predictions of four different event generators. One of them is the recently developed APACIC++ generator which performs a massive matrix element calculation matched to a parton shower followed by string fragmentation. The four-jet rate is used to measure alphas in the next-to-leading-order approximation yielding alphas(MZ2) = 0.1175 +/- 0.0030. The running of alphas determined by using four-jet events has been tested. The logarithmic energy slope is measured to be dαs-1 / dlog Ecm = 1.14 +/- 0.36. Since the analysis is based on four-jet final states it represents an alternative approach to previous DELPHI alphas measurements using event shape distributions.