CERN Accelerating science

Thesis
Report number	WUB-DIS-2002-06 ; WU-B-DIS-2002-06 ; CERN-THESIS-2002-085
Title	Tests der pertubativen QCD in der e+e Annihilation
Related title	Tests of perturbation QCD in the e+ e- annihilation. (In German)
Author(s)	Passon, Oliver (Wuppertal U.)
Publication	2002 - 187.
Thesis note	PhD : Wuppertal U. : 2002
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LEP ; DELPHI
Abstract	This thesis presents the DELPHI measurement of event shape distributions and inclusive spectra in e+e- annihilation at LEP between 183 and 207 GeV. These data have been reprocessed in 2001 and the results supersede some older DELPHI measurements at the corresponding energies [1, 2, 3, 4, 5]. The differential distributions in Ep = ln 1/xp and their maxima E* are compared with predictions in the MLLA/LPHD framework. These tests support the manifestation of coherence effects on the hadronic level. From the event shapes Thrust, C parameter heavy jet mass wide and total jet broadening s is extracted with four different methods: The differential distributions are compared to predictions in O s pure NLLA and O s + NLLA logR folded with fragmentation models For the mean values s is extracted using an analytical power correction ansatz. The s values are combined with results obtained at other LEP energies and at and around MZ This allows both a combined measurement of s and a test of the running of s The smallest uncertainties are obtained from the measurement of mean values with power corrections Here the results are: sMZ = 0.1184 +- 0.0004 (stat) +- 0.0008 (sys.ex.) +- 0.0008 (had) +- 0.0031 (scale) + 0.1184 +- 0.0033 (tot) and for the measurement of the function d s d ln Q stat sys The last number has to be compared with the QCD value of 1.27 and the expected slope in an QCD gluino scenario of 0.89. Another way to measure the function directly is to compare the energy dependence of inclusive quantities like mean values of event shape observables with the RGI perturbation theory [24] For the quantity R = {1 - T }/A using also low energy data we obtain: Q dR dQ = 4.21 +- 0.18. This number has to be compared with the QCD expectation of 4.14 and the QCDgluino value of 2.76

Corresponding record in: Inspire