A Study of Jet Rates and Measurement of [alpha][sub S] at the Z[sup 0] Resonance

A Study of Jet Rates and Measurement of [alpha][sub S] at the Z[sup 0] Resonance

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Published: 1993

Total Pages: 156

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This experiment was performed with the SLD detector at the Stanford Linear Accelerator Center. Only charged tracks measured in the central drift chamber were used for the measurement of the jet production rates. The value of the strong coupling [alpha][sub s](M[sub Z][sup o]) is determined from the production rates of jets in hadronic Z[sup 0] decays in e[sup +] e[sup [minus]] annihilations. The relative jet rates are obtained using the JADE-type algorithms. The results are compared with the jet rates obtained from a new jet algorithm proposed by N. Brown et al. called the Durham'' algorithm. The data can be well described by O([alpha][sub s][sup 2]) QCD calculations and by QCD shower model calculations. A fit of the theoretical predictions to the data taken with the SLD yields a value, [alpha][sub s](M[sub Z][sup o]) = 0.120 [plus minus] 0.002(stat.) [plus minus] 0.003(exp.)[sub [minus]0.009][sup +0.011](theor.). The error is dominated by the theoretical uncertainties. The measurement is compared with results from other experiments and it is shown that the value obtained for [alpha][sub s] agrees well with these results and furthermore supports the evidence for the running of the strong coupling, consistent with the non-Abelian nature of QCD. The Stanford Linear Collider (SLC) can deliver partially longitudinally polarized electrons to the interaction point. Jet production rates and values for [alpha][sub s] are calculated both for right-handed and left-handed initial state electrons. All results are consistent with the unpolarized result, as predicted by the Standard Model.


A Study of Jet Rates and Measurement of [alpha]{sub S} at the Z° Resonance

A Study of Jet Rates and Measurement of [alpha]{sub S} at the Z° Resonance

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Published: 1992

Total Pages: 14

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We present jet rates in hadronic decays of Z° bosons measured by the SLD experiment at SLAC. The data are analyzed in terms of the JADE and recently proposed Durham algorithms, and are found to be in agreement with similar measurements by the LEP experiments, and also with the predictions of perturbative QCD and fragmentation Monte Carlo models of hadron production. After correction for hadronization effects the 2, 3 and 4-jet rates are well described by [Omicron]([alpha]{sub s}2) perturbative QCD calculations. From fits to the differential 2-jet distribution the strong coupling [alpha]{sub s}(M{sub Z}) is measured to be [alpha]{sub s}(M{sub Z}) = 0.119 ± 0.002(stat.) ± 0.003(exp.syst.) ± 0.014(theory) (preliminary). The largest contribution to the error arises from the theoretical uncertainty in choosing the QCD renormalization scale.


A Study of Jet Rates and Measurement Of?{sub S} at the Z° Resonance

A Study of Jet Rates and Measurement Of?{sub S} at the Z° Resonance

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Publisher:

Published: 1993

Total Pages: 156

ISBN-13:

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This experiment was performed with the SLD detector at the Stanford Linear Accelerator Center. Only charged tracks measured in the central drift chamber were used for the measurement of the jet production rates. The value of the strong coupling?{sub s}(M{sub Z}{sup o}) is determined from the production rates of jets in hadronic Z° decays in e e− annihilations. The relative jet rates are obtained using the JADE-type algorithms. The results are compared with the jet rates obtained from a new jet algorithm proposed by N. Brown et al. called the D̀̀urham ̀̀algorithm. The data can be well described by O(?{sub s}2) QCD calculations and by QCD shower model calculations. A fit of the theoretical predictions to the data taken with the SLD yields a value,?{sub s}(M{sub Z}{sup o}) = 0.120 ± 0.002(stat.) ± 0.003(exp.){sub -0.009}{sup +0.011}(theor.). The error is dominated by the theoretical uncertainties. The measurement is compared with results from other experiments and it is shown that the value obtained for?{sub s} agrees well with these results and furthermore supports the evidence for the running of the strong coupling, consistent with the non-Abelian nature of QCD. The Stanford Linear Collider (SLC) can deliver partially longitudinally polarized electrons to the interaction point. Jet production rates and values for?{sub s} are calculated both for right-handed and left-handed initial state electrons. All results are consistent with the unpolarized result, as predicted by the Standard Model.


Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports

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Published: 1995

Total Pages: 376

ISBN-13:

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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.


Measurement of [alpha][sub S] from Hadronic Event Observables at the Z[sup 0] Resonance

Measurement of [alpha][sub S] from Hadronic Event Observables at the Z[sup 0] Resonance

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Published: 2005

Total Pages:

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The authors have measured the strong coupling [alpha][sub s] using hadronic decays of Z[sup 0] bosons collected by the SLD experiment at SLAC. The data were compared with QCD predictions both at fixed order, O([alpha][sub s][sup 2]), and including resummed analytic formulae based on the leading and next-to-leading logarithm approximation. The study includes event shapes, jet rates, and particle correlations. They checked the consistency between [alpha][sub s] extracted from these different measures and found the dominant uncertainty on [alpha][sub s] to be from uncalculated higher order contributions.