A study of the energy evolution of event shape distributions and their means with the DELPHI detector at LEP

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dc.creatorThe DELPHI Collaboration
dc.creatorAbdallah, J.
dc.date2003-07-17
dc.date.accessioned2026-07-07T12:02:00Z
dc.date.available2026-07-07T12:02:00Z
dc.descriptionInfrared and collinear safe event shape distributions and their mean values are determined in e+e- collisions at centre-of-mass energies between 45 and 202 GeV. A phenomenological analysis based on power correction models including hadron mass effects for both differential distributions and mean values is presented. Using power corrections, alpha_s is extracted from the mean values and shapes. In an alternative approach, renormalisation group invariance (RGI) is used as an explicit constraint, leading to a consistent description of mean values without the need for sizeable power corrections. The QCD beta-function is precisely measured using this approach. From the DELPHI data on Thrust, including data from low energy experiments, one finds beta_0 = 7.86 +/- 0.32 for the one loop coefficient of the beta-function or, assuming QCD, n_f = 4.75 +/- 0.44 for the number of active flavours. These values agree well with the QCD expectation of beta_0=7.67 and n_f=5. A direct measurement of the full logarithmic energy slope excludes light gluinos with a mass below 5 GeV.
dc.description45 pages, 17 figures, Accepted by Eur. Phys. J. C
dc.identifierhttps://arxiv.org/abs/hep-ex/0307048
dc.identifierhttp://arxiv.org/abs/hep-ex/0307048
dc.identifierEur.Phys.J.C29:285-312,2003
dc.identifierdoi:10.1140/epjc/s2003-01198-0
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/207291
dc.subjectHigh Energy Physics - Experiment
dc.titleA study of the energy evolution of event shape distributions and their means with the DELPHI detector at LEP
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