The measurement of \(\alpha_s\) from event shapes with the DELPHI detector at the highest LEP energies

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Abstract.

Hadronic event shape distributions are determined from data in e + e - collisions between 183 and 207 GeV. From these the strong coupling \(\alpha_s\) is extracted in \({\cal{O}}(\alpha_s^2)\) , NLLA and matched \({\cal{O}}(\alpha_s^2)\) + NLLA theory. Hadronisation corrections evaluated with fragmentation model generators as well as an analytical power ansatz are applied. Comparing these measurements to those obtained at and around M Z allows a combined measurement of \(\alpha_s\) from all DELPHI data and a test of the energy dependence of the strong coupling.

Received: 19 March 2004, Revised: 13 May 2004, Published online: 6 August 2004