Charged hadron production ine+e− annihilation is studied in the 7 to 10 GeV CM energy region and at the Υ (9.46) and Υ′ (10.01) resonances with the LENA detector at DORIS. The statistical moments of the charged multiplicities are studied. The data show KNO scaling behaviour and suggest the presence of long range correlations. An average charged multiplicityrise of Δn(Υ)=0.55±0.19 and Δn(Υ′)=1.26±0.29 over the continuum is observed for the Υ and Υ′ direct decays. The jet structure of the Υ and Υ′ direct decays is investigated using the charged particles. The polar angular distributions of the jet axis behave like 1+α(T) cos2θ with 〈α(T)〉Υ=0.7±0.3 and 〈α(T)〉Υ′=0.6±0.4. The 〈α(T)〉Υ value is in agreement with the QCD vector gluon assignment and excludes scalar gluons by more than four standard deviations.
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CHARGED HADRON MEASUREMENTS ARE TAKEN FROM R.A. PERCHANOK, PHD THESIS, CORNELL UNIVERSITY (1983).
CHARGED HADRON MEASUREMENTS ARE TAKEN FROM G.J. RUCINSKI, PHD THESIS, CORNELL UNIVERSITY (1983).
In this paper, results are presented from a study of the hadronic final states in e+e− annihilation at 29 GeV. The data were obtained with the High Resolution Spectrometer (HRS) at the SLAC PEP e+e− colliding-beam facility. The results are based on 6342 selected events corresponding to an integrated luminosity of 19.6 pb−1. The distributions of the events in sphericity (S), thrust (T), and aplanarity (A) are given and compared to other e+e− data in the same energy range. We measure 〈S〉=0.130±0.003±0.010 and 〈1-T〉=0.100±0.002. The sphericity distribution is compared to sphericity measurements made for beam jets in hadronic collisions as well as jets studied in neutrino scattering. The data sample is further reduced to 4371 events with the two-jet selections, S≤0.25 and A≤0.1. The single-particle distributions in the longitudinal and transverse directions are given. For low values of the momentum fraction (z=2p/W), the invariant distribution shows a maximum at z∼0.06, consistent with a QCD expectation. The data at high Feynman x (xF) show distribution consistent with being dominated by a (1-xf)2 variation for the leading quark-meson transition. The rapidity distribution shows a shallow central minimum with a height (1/NevdNh/dY‖Y=0=2.3±0.02±0.07. The mean charged multiplicity is measured to be 〈nch〉=13.1±0.05±0.6. The mean transverse momentum relative to the thrust axis 〈pT〉 rises as a function of z to a value of 0.70±0.02 GeV/c for z≳0.3. The distributions are compared to those measured in other reactions.
New values supplied 6.7.87 by M.Derrick.
No description provided.
New values supplied 6.7.87 by M. Derrick.
We compare the particle flow in the event plane of three-jet qq¯g (quark-antiquark-gluon) events with the particle flow in radiative annihilation events qq¯γ (quark-antiquark-photon) for similar kinematic configurations. In the angular region between quark and antiquark jet, we find a significant decrease in particle density for qq¯g as compared to qq¯γ. This effect is predicted in QCD as a result of destructive interference between soft-gluon radiation from quark, antiquark, and hard gluon.
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The particle flow distributions in the event plane of 3-jet\((e^ +e^ -\to q\bar qg)\) and of radiative 2-jet\((e^ +e^ -\to q\bar q\gamma )\) events are compared at a centre of mass energy of 35 GeV. The number of particles in the angular region opposite to the gluon in\(q\bar qg\) events is found to be significantly reduced relative to the number of particles in the region opposite to the hard photon in\(q\bar q\gamma \) events. This depletion is expected from the “string effect” observed in 3-jet events. It can be explained within the framework of QCD as arising from soft gluon interference.
Data requested from authors.
We report on an analysis of the multiplicity distributions of charged particles produced ine+e− annihilation into hadrons at c.m. energies between 14 and 46.8 GeV. The charged multiplicity distributions of the whole event and single hemisphere deviate significantly from the Poisson distribution but follow approximate KNO scaling. We have also studied the multiplicity distributions in various rapidity intervals and found that they can be well described by the negative binomial distribution only for small central intervals. We have also analysed forward-backward multiplicity correlations for different energies and selections of particle charge and shown that they can be understood in terms of the fragmentation properties of the different quark flavours and by the production and decay of resonances. These correlations are well reproduced by the Lund string model.
RATIO of MULT/DISPERSION for the whole event to that for the single hemisphere data.
Complete event multiplicities.
Single hemisphere multiplicities.
Inclusive charged particle production ine+e− annihilation into hadrons is studied in terms of the particle fractional momentumxp. Thexp distribution for gluon jets is extracted by comparing two data samples measured in the TASSO detector: nearly symmetric three jet events at centre-of-mass energyW∼35 GeV and two jet events atW∼22 GeV, yielding quark and gluon jets of similar energies (∼11.5 GeV). No significant difference is observed between quark and gluon jets. Monte Carlo models based on parton showers describe the trend and energy variation of the data better than a model with second order matrix element in αs.
2 JET data at sqrt(s) = 35 GeV.
3 JET data at sqrt(s) = 22 GeV.
Gluon jet data at sqrt(s) = 11.5 GeV.
We have measured inclusive distributions for charged particles in hadronic decays of the Z boson. The variables chosen for study were charged-particle multiplicity, scaled momentum, and momenta transverse to the sphericity axes. The distributions have been corrected for detector effects and are compared with data from e+e− annihilation at lower energies and with the predictions of several QCD-based models. The data are in reasonable agreement with expectations.
Mean corrected charged particle multiplicity.
Corrected charged particle X distributions. Errors are statistical and systematic combined.
Corrected charged particle PTIN distributions. Errors are statistical and systematic combined.
Hadronic decays of Z 0 bosons are studied in the Delphi detector. Global event variables and singel particles inclusive distributions are compared with QCD-based predictions. The mean charged multiplicity is found to be 20.6±1.0 (stat+syst). The mean values of the sphericity, aplanarity, thrust, minor value, p in T and p out T are compared with values found at lower energy e + e − colliders.
Corrected Sphericity distribution. Statistical errors only.
Corrected Aplanarity distribution. Statistical errors only.
Corrected Q3-Q2 distribution. Statistical errors only.
We study the inclusive momentum distribution of charged particles in multihadronic events produced in e + e − annihilations at E CM ∼ M (Z 0 ). We find agreement with the analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from CM energies between 14 and 91 GeV, we study the dependence of the inclusive momentum distribution on the centre of momentum energy. We find that the analytical formulae describe the data over the entire energy range. Both the momentum distribution at a fixed energy and the change with energy are described by QCD shower Monte Carlo's which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and momentum spectra.
Statistical errors only. Overall systematic error of 5%.
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