Studies of hadronic event structure in e+ e- annihilation from 30-GeV to 209-GeV with the L3 detector

The L3 collaboration Achard, P. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Rept. 399 (2004) 71-174, 2004.
Inspire Record 652683 DOI 10.17182/hepdata.54900

In this Report, QCD results obtained from a study of hadronic event structure in high energy e^+e^- interactions with the L3 detector are presented. The operation of the LEP collider at many different collision energies from 91 GeV to 209 GeV offers a unique opportunity to test QCD by measuring the energy dependence of different observables. The main results concern the measurement of the strong coupling constant, \alpha_s, from hadronic event shapes and the study of effects of soft gluon coherence through charged particle multiplicity and momentum distributions.

68 data tables

Jet fractions using the JADE algorithm as a function of the jet resolution parameter YCUT at c.m. energy 130.1 GeV.

Jet fractions using the JADE algorithm as a function of the jet resolution parameter YCUT at c.m. energy 136.1 GeV.

Jet fractions using the JADE algorithm as a function of the jet resolution parameter YCUT at c.m. energy 161.3 GeV.

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Inclusive production of pi0, eta, eta'(958), K0(S) and Lambda in two- and three-jet events from hadronic Z decays.

The ALEPH collaboration Barate, R. ; Decamp, D. ; Ghez, Philippe ; et al.
Eur.Phys.J.C 16 (2000) 613, 2000.
Inspire Record 507531 DOI 10.17182/hepdata.49106

The production rates and the inclusive cross sections of the isovector meson${\rm \pi^0}$, the isoscalar mesons$\eta$and

25 data tables

Inclusive cross section for PI0 production in hadronic events.

Inclusive cross section for ETA production in hadronic events.

Inclusive cross section for ETAPRIME production in hadronic events.

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A study of parton fragmentation in hadronic Z0 decays using Lambda Antilambda correlations.

The OPAL collaboration Abbiendi, G. ; Ackerstaff, K. ; Alexander, G. ; et al.
Eur.Phys.J.C 13 (2000) 185-195, 2000.
Inspire Record 474010 DOI 10.17182/hepdata.49312

The correlated production of Lambda and Lambdabar baryons has been studied using 4.3 million multihadronic Zo decays recorded with the OPAL detector at LEP. Di-lambda pairs were investigated in the full data sample and for the first time also in 2-jet and 3-jet events selected with the k_t algorithm. The distributions of rapidity differences from correlated Lambda-Lambdabar pairs exhibit short-range, local correlations and prove to be a sensitive tool to test models, particularly for 2-jet events. The JETSET model describes the data best but some extra parameter tuning is needed to improve agreement with the experimental results in the rates and the rapidity spectra simultaneously. The recently developed modification of JETSET, the MOdified Popcorn Scenarium (MOPS), and also HERWIG do not give satisfactory results. This study of di-lambda production in 2- and 3-jet events supports the short-range compensation of quantum numbers.

5 data tables

Average multipicity of LAMBDA pairs in hadronic events.

Average multipicity of LAMBDA pairs in 2-Jet events.

Average multipicity of LAMBDA pairs in 3-Jet events.

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A Model independent measurement of quark and gluon jet properties and differences

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 68 (1995) 179-202, 1995.
Inspire Record 396179 DOI 10.17182/hepdata.47862

None

3 data tables

THETA is the angle between hadron and jet's axis. CONST is the parameter used in jet's definition (see text).

CONST is the parameter used in jet's definition (see text).

CONST is the parameter used in jet's definition (see text).


A Study of mean subjet multiplicities in two and three jet hadronic Z0 decays

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 63 (1994) 363-376, 1994.
Inspire Record 372997 DOI 10.17182/hepdata.48236

This paper describes an analysis of sub-jet multiplicities, which are expected to be sensitive to the properties of soft gluon radiation, in hadronic decays of theZ0. Two- and three-jet event samples are selected using thek⊥ jet clustering algorithm at a jet resolution scaley1. The mean sub-jet multiplicity as a function of the sub-jet resolution,y0, is determined separately for both event samples by reapplying the same jet algorithm at resolution scalesy0<y1. These measurements are compared with recent perturbative QCD calculations based on the summation of leading and next-to-leading logarithms, and with QCD Monte Carlo models. The analytic calculations provide a good description of the sub-jet multiplicity seen in three- and two-jet mvents in the perturbative region (y0≈y1)), and the measured form of the data is in agreement with the expectation based on coherence of soft gluon radiation. The analysis provides good discrimination between Monte Carlo models, and those with a coherent parton shower are preferred by the data. The analysis suggests that coherence effects are present in the data.

4 data tables

Ratio of multiplicities of sub-jets from 3 and 2 jet samples. Data are corrected to the hadron level and have combined statistical and systematic errors.

Sub-jet multiplicity for 3 jet sample. Data corrected to the hadron level and have combined statistical and systematic errors.

Sub-jet multiplicity for 2 jet sample. Data corrected to the hadron level and have combined statistical and systematic errors.

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QCD studies using a cone based jet finding algorithm for e+ e- collisions at LEP

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 63 (1994) 197-212, 1994.
Inspire Record 373000 DOI 10.17182/hepdata.48238

We describe a cone-based jet finding algorithm (similar to that used in\(\bar p\)p experiments), which we have applied to hadronic events recorded using the OPAL detector at LEP. Comparisons are made between jets defined with the cone algorithm and jets found by the “JADE” and “Durham” jet finders usually used ine+e− experiments. Measured jet rates, as a function of the cone size and as a function of the minimum jet energy, have been compared with O(αs2) calculations, from which two complementary measurements\(\alpha _s \left( {M_{Z^0 } } \right)\) have been made. The results are\(\alpha _s \left( {M_{Z^0 } } \right)\)=0.116±0.008 and\(\alpha _s \left( {M_{Z^0 } } \right)\)=0.119±0.008 respectively, where the errors include both experimental and theoretical uncertainties. Measurements are presented of the energy flow inside jets defined using the cone algorithm, and compared with equivalent data from\(\bar p\)p interactions, reported by the CDF collaboration. We find that the jets ine+e− are significantly narrower than those observed in\(\bar p\)p. The main contribution to this effect appears to arise from differences between quark- and gluon-induced jets.

16 data tables

Measured 2 jet production rate as a function of EPSILON, the minimum energy of a jet for a fixed cone radius R = 0.7 radians.

Measured 2 jet production rate as a function of R, the jet cone radius, for a fixed value of the minimum jet energy, EPSILON, of 7 GeV.

Measured 3 jet production rate as a function of EPSILON, the minimum energy of a jet for a fixed cone radius R = 0.7 radians.

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Charged particle multiplicity distributions for fixed number of jets in Z0 hadronic decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.
Z.Phys.C 56 (1992) 63-76, 1992.
Inspire Record 334948 DOI 10.17182/hepdata.14533

The multiplicity distributions of charged particles in full phase space and in restricted rapidity intervals for events with a fixed number of jets measured by the DELPHI detector are presented. The data are well reproduced by the Lund Parton Shower model and can also be well described by fitted negative binomial distributions. The properties of these distributions in terms of the clan model are discussed. In symmetric 3-jet events the candidate gluon jet is found not to be significantly different in average multiplicity than the mean of the other two jets, thus supporting previous results of the HRS and OPAL experiments. Similar results hold for events generated according to the LUND PS and to the HERWIG models, when the jets are defined by the JADE jet finding algorithm. The method seems to be insensitive for measuring the color charge ratio between gluons and quarks.

3 data tables

Corrected charged particle multiplicity for jet resolution parameter YCUT = 0.01.

Corrected charged particle multiplicity for jet resolution parameter YCUT = 0.02.

Corrected charged particle multiplicity for jet resolution parameter YCUT = 0.04.


A Study of the recombination scheme dependence of jet production rates and of alpha-s (m(Z0)) in hadronic Z0 decays

The OPAL collaboration Akrawy, M.Z. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 49 (1991) 375-384, 1991.
Inspire Record 299833 DOI 10.17182/hepdata.15085

The error includes the experimental uncertainties (±0.003), uncertainties of hadronisation corrections and of the degree of parton virtualities to which the data are corrected, as well as the uncertainty of choosing the renormalisation scale.

9 data tables

Jet production rates using the E0 recombination scheme.

Jet production rates using the E recombination scheme.

Jet production rates using the p0 recombination scheme.

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A Study of jet rates and measurement of alpha-s at the Z0 resonance

Lauber, Jan A. ; Nauenberg, U. ;
SLAC-0413, 1993.
Inspire Record 353248 DOI 10.17182/hepdata.18664

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 $\alpha_s (M_{Z^0})$ is determined from the production rates of jets in hadronic $Z^0$ 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 "Durham" algorithm. The data can be well described by $\mathcal{O}(\alpha^2_s)$ QCD calculations and by QCD shower model calculations. A fit of the theoretical predictions to the data taken with the SLD yields a value$\alpha_s(M_{Z^0})$ = $0.120 \pm 0.002(stat.) \pm 0.003(exp.)^{+0.011}_{-0.009}(theor.)$ 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 $\alpha_s$ 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 a, 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.

9 data tables

Jet production rates using the JADE recombination scheme.

Jet production rates using the DURHAM recombination scheme.

Jet production rates using the E recombination scheme.

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A Global determination of alpha-s (M(z0)) at LEP

The OPAL collaboration Acton, P.D. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 55 (1992) 1-24, 1992.
Inspire Record 333079 DOI 10.17182/hepdata.14606

The value of the strong coupling constant,$$\alpha _s (M_{Z^0 } )$$, is determined from a study of 15 d

16 data tables

Differential jet mass distribution for the heavier jet using method T. The data are corrected for the finite acceptance and resolution of the detector and for initial state photon radiation.

Differential jet mass distribution for the jet mass difference using methodT. The data are corrected for the finite acceptance and resolution of the detec tor and for initial state photon radiation.

Differential jet mass distribution for the heavier jet using method M. The data are corrected for the finite acceptance and resolution of the detector and for initial state photon radiation.

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