A.A. Seidl

Rapidity Dependence of the Charged Particle Multiplicity Distributions in e+ e- Annihilation at 29-GeV

Abstract The charged particle multiplicity distribution for e+e− annihilations at s = 29 GeV has been measured using the High Resolution Spectrometer at PEP. The multiplicity distribution, expressed as a function of the mean, shows KNO scaling when compared to e+e− data at other energies. Multiplicity distributions for particles selected in different central rapidity spans are presented. All of these are well presented by the Negative binomial distribution. As the rapidity span is narrowed, the distributions become broader and approach a constant value of the parameter k.

Production of γ, Λ°, Ks° and Λ° in pp collisions at 102 GeV/c☆

Abstract We have measured cross section for γ , K S °, Λ and Λ production at 102 GeV/ c and find: σ ( γ ) = 170 ± 16 mb ., σ ( K S °) = 4.6 ± 0.5 mb ., σ ( Λ ) = 3.2 ± 0.4 mb ., and σ( Λ ) = 0.23 ± 0.10 mb. Both 〈 n π °〉 and 〈 n Ks °〉 appear to rise linearly with n - while the ratio 〈 n Ks °〉/〈 n π °〉 is approximately independent of n - . The integrated invariant cross section as a function of x as well as d σ /d y and d σ /d p T 2 are presented and compared with other data.

Comparison of charged particle multiplicities in quark and gluon jets produced in e+e- annihilation at 29 GeV

The charged particle multiplicities of the quark and gluon jets in the three-fold symmetric e+e− → qqg events at √s = 29 GeV have been studied using the high resolution spectrometer at PEP. A value of 〈n〉g = 6.7−2.1+1.1±1.0 for gluon jet s with an energy of 9.7−2.0+1.5 GeV is measured. The ratio, 〈n〉g/〈n〉q, is 1.29−0.41+0.21±0.20, which i s significantly lower than the value of 94 naively expected from the ration of the gluon-to-quark color charges.

Quark jets from antineutrino interactions (I). Net charge and factorization in the quark jets

Abstract We investigate properties of the hadron jets produced in deep inelastic antineutrino-nucleon charged current interactions in the Fermilab 15 foot bubble chamber. Our detailed analysis of the jet net charge provides evidence for the quark origin of the hadron jets. The factorization hypothesis for the inclusive one-particle cross section is found to be valid.

Charged current events with neutral strange particles in high-energy antineutrino interactions

The results of a study of strange particle production in charged current νμN interactions in the Fermilab 15 ft bubble chamber filled with a heavy NeH2 mixture are presented. Production rates and average multiplicities of K0s and Λs as functions of W2 and Q2 are given. The experimental data agree well with the quark-parton model predictions if a yield of 0.06 ± 0.02 of K0s and Λs from charm production is included. Upper limits for D-meson production are given and the shape of the charmed quark fragmentation function is discussed. Inclusive production of the K∗(890) and Σ(1385) resonances is measured and it is shown that only about 5% of the K0 mesons and Λ hyperons results from resonance decays. Relative production rates of neutral strange particles on proton and neutron targets are studied.

Neutral K*(890) and ρ0 meson production in e+e- annihilation at ;s=29GeV

Abstract The production of neutral K∗(890) and ρ0 mesons was studied in e+e− annihilation at s =29 GeV using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to π0 and K0 production. The measured multiplicities are 0.84±0.08 ϱ0 mesons and 0.57±0.09 K ∗0 (890) mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model.

Charm Quark Production and Fragmentation in

Abstract The electroweak production asymmetry and the decay fragmentation function for e + e − → c c have been measured at s = 29 GeV using charged D ∗ production over the full kinematic range. The data were taken at PEP using the High Resolution Spectrometer. The measured asymmetry is −0.12 ± 0.08. The total production cross section in units of the point cross section corrected for initial state radiation is R D ∗ = 2.7 ± 0.9 .

e^+ e^-

Abstract Separate samples of charm quark and light quark (u, d, s) jets have been isolated in an experiment studying e + e − annihilations at s = 29 GeV . The results come from data corresponding to an integrated luminosity of 111 pb −1 collected by the High Resolution Spectrometer. Differences were observed in charged multiplicities, momentum distributions, and rapidity of the size expected from the different fragmentation functions and leading particle decay properties of the two samples.

Annihilation at 29-{GeV}

Abstract We investigate the net change in the current fragmentation region in antineutrino-nucleon charged current interactions in the Fermilab 15 ft bubble chamber. Support is presented for the d-quark origin of the forward hadrons in the hadron center-of-mass system. An extrapolation of the net charge to infinite center-of-mass energy is performed giving as a result 〈Q〈 v =− (0.44 ± 0.09) . Combining this result with the result obtained using our v events in the same experiment we obtain the value 0.98 ± 0.15 for the charge difference between the fragmenting quarks in v and v charged current events.

Comparison of light quark and charm quark fragmentation

Abstract We have used the ratio between the production rates of K 0 s and π − s in antineutrino-nucleon interactions in the Fermilab 15 ft bubble chamber to measure the size of the SU (3) symmetry violation in the production of quark-antiquark pairs to be 0.27±0.04. This value is significantly larger than the value obtained from a recent ep experiment. There is no apparent dependence of the K 0 π − ratio with W 2 , Q 2 , x b or p T 2 .