# QCD studies in $e^{+}e^{-}$ annihilation from 30 GeV to 189 GeV

3 CMS
IP2I Lyon - Institut de Physique des 2 Infinis de Lyon
Abstract : We present results obtained from a study of the structure of hadronic events recorded by the L3 detector at various centre-of-mass energies.The distributions of event shape variables and the energy dependence of their mean values are measured from 30 GeV to 189 GeV and compared with various QCD models. The energy dependence of the moments of event shape variables is used to test a power law ansatz for the non-perturbativecomponent. We obtain a universal value of the non-perturbative parameter$\alpha_{0}$ = 0.537 $\pm$ 0.073. From a comparison with resummed$\cal{O} \alpha_{\rm s}^{2})$ QCD calculations, we determine thestrong coupling constant at each of the selected energies. The measurements demonstrate the running of $\alpha_{\rm s}$ as expected in QCD with a value of$\alpha_{\rm s} (m_{\rm Z})$ = 0.1215 $\pm$ 0.0012 (exp) $\pm$ 0.0061 (th).
Document type :
Journal articles

Cited literature [25 references]

http://hal.in2p3.fr/in2p3-00005412
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Submitted on : Monday, October 2, 2000 - 9:16:29 AM
Last modification on : Friday, September 10, 2021 - 1:50:04 PM
Long-term archiving on: : Friday, May 29, 2015 - 5:01:01 PM

### Identifiers

• HAL Id : in2p3-00005412, version 1

### Citation

M. Acciarri, P. Achard, O. Adriani, M. Aguilar-Benitez, J. Alcaraz, et al.. QCD studies in $e^{+}e^{-}$ annihilation from 30 GeV to 189 GeV. Physics Letters B, Elsevier, 2000, 489, pp.65-80. ⟨in2p3-00005412⟩

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