A. Shapira

Charged multiplicity distributions and correlations ine+e− annihilation at PETRA energies

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.

D*± production by e+e- annihilation near 34.4 GeV cm energy

Abstract D∗± production via e+e−→D∗±X has been measured at an average CM energy of 34.4 GeV. The D∗± energy spectrum is hard, with a maximum near χ = 0.6. The size of the D∗ cross section, R D ∗ = σ( e + e − → D ∗ X ) σ μμ = 2.50 ± 0.64 ± 0.88 (assuming R D ∗0 = R D ∗+ ) indicates that a large fraction of charm quark production yields D∗ mesons. The D∗± angular distribution exhibits a forward—backward asymmetry, A = −0.28 ± 0.13. This is consistent with that expected in the standard theory for weak neutral currents and leads to |gAc| = 0.89 ± 0.44 for the axial vector coupling of the charm quark.

Analysis of multijet final states in e+e− annihilation

Abstract Data accumulated by the TASSO detector across the whole range of energies spanned at PETRA, 12⩽ s ⩽46.8 GeV , have been analysed in terms of cluster algorithms. Using parameters optimised at 35 GeV CM energy, three perturbative QCD+fragmentation models were compared with the data. The O( α s 2 ) model gives too few 4,5- cluster events, implying that higher order QCD contributions are required to describe the data. The parton cascade model, incorporating many orders in perturbation theory, gives a better description of the rates of ⩾ 4 clusters, but shows a lack of hard gluon emission by giving too few 3-, and too many 2-cluster events. When hard gluon emission is taken into account, by the cascade model incorporating the O( α s ) matrix element, all cluster rates are reproduced well. All the models describe the trend of the evolution of the cluster rates between 〈 s 〉 = 14 and 43.8 GeV. We find that the rate of 3-jet events seen in the data decreases as s increases in a manner consistent with the Q 2 dependence of α s as predicted by QCD.

Inclusive production of neutral strange particles by 147 GeV/cπ+/K+/p interactions in hydrogen

Results are presented from a study of inclusive neutral strange particle production by a 147 GeV/c tagged π+/K+/p beam in the Fermilab 30-inch hydrogen bubble chamber. The experiment made use of the proportional hybrid spectrometer system. Results are based on 995 KS0, 485 Λ, and 83 Λ found in a sample of 132 000 pictures. Cross sections are given for inclusive production of these particles by each of the three beam particles, and comparisons are made with measurements at other energies. Topological cross sections are also calculated, and KNO multiplicity scaling is investigated. Distributions are presented of invariant cross sections as functions of the Feynman scaling variable x and c.m. rapidity y. The transverse momentum-squared distributions with their fitted slopes are also given. Comparisons are made of the production characteristics for the three beam types.

A measurement of σtot(e+e− → hadrons) for cm energies between 12.0 and 36.7 GeV

Abstract The ration R = σ (e + e − → hadrons) σ μμ was measured between 12.0 and 36.7 GeV c.m. energy W with a precision of typically ± 5.2%. R is found to be constant with an average R = 4.01 ± 0.03 (stat) ± (syst.) for W ⩾ 14 GeV. Quarks are found to be point-like, the mass parameter describing a possible quark form-factor being larger than 186 GeV. Fits including QCD corrections and a weak neutral-current contribution are presented.

Charged pion, kaon, proton and antiproton production in high energy e+e− annihilations

Abstract Production of pions, kaons, protons and antiprotons has been studied in e + e − annihilations at 12 and 30 GeV centre of mass energy using time of flight techniques. The fractional yield of charged kaons and baryons appears to rise with outgoing particle momentum. At our highest energy at least 40% of e + e − annihilations into hadrons are estimated to contain baryons.

Particle correlation observed ine+e− annihilations into hadrons at c.m. Energies between 29 and 37 GeV

We have studied the correlations between charged particles produced ine+e− annihilations into hadrons at c.m. energies between 29 and 37 GeV. We have analysed the correlations between the charged multiplicities of the jets and the two particle rapidity and charge correlations. No evidence for correlations between the multiplicities of the two jets is found. Two particle short range rapidity and charge correlations are observed, indicating that particles cluster in rapidity and that their charges compensate locally. An extensive study of these correlation effects by QCD Monte Carlo calculations was performed. Evidence for charge correlations due to Bose-Einstein statistics is also observed.

Pion, kaon and proton cross sections ine+e− annihilation at 34 GeV and 44 GeV c.m. energy

AbstractThe inclusive production of π± andK± mesons and of protons and antiprotons ine+e− annihilations has been measured at 34 GeV and 44 GeV center of mass energy; in addition π± mesons have been measured at 44 GeV c.m. energy. Differential cross sections and particle yields are given. At 34 GeV average multiplicities are:

Cross sections of final states produced in KN interactions at 3 GeV/c

\begin{gathered} \left\langle {n\left( {\pi ^ \pm } \right)} \right\rangle = 10.9 \pm 0.5,\left\langle {n\left( {K^ \pm } \right)} \right\rangle = 1.76 \pm 0.20, \hfill \\ \left\langle {n\left( {p + \bar p} \right)} \right\rangle = 0.67 \pm 0.06 \hfill \\ \end{gathered}