R. DeBonte

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.

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.

Evidence for the decay τ+→π+ηντ

Abstract The inclusive production of η mesons in tau lepton decay has been studied using the High Resolution Spectrometer at the PEP e + e - facility. The data sample corresponds to an integrated luminosity of 300 pb −1 and the storage ring was operated at GeV. The η production appeaars to be only compatible with the decay τ + →π + η ν , which violates isospin and G -parity conservation. The branching ratio of 5.1±1.5% explains much of the current discrepancy between the one-prong topological branching ratio and the sum of the individual one-prong modes.

Charged particle multiplicity correlations in pp̄ collisions at s=0.3−1.8 TeV

Abstract The correlations between charged particle multiplicitie produced in forward and backward pseudorapidity regions in pp interactions have been measured with a 240 element scintillator hodoscope. The correlation coefficient and the variance of the difference of multiplicities in the two pseudorapidity regions were deterermined for s =0.3−1.8 TeV . These results have been interpreted in terms of a cluster model of particle production.

Charged particle multiplicity correlations in

Abstract The correlations between charged particle multiplicitie produced in forward and backward pseudorapidity regions in pp interactions have been measured with a 240 element scintillator hodoscope. The correlation coefficient and the variance of the difference of multiplicities in the two pseudorapidity regions were deterermined for s =0.3−1.8 TeV . These results have been interpreted in terms of a cluster model of particle production.

p\bar{p}

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.

collisions at

Transverse momentum spectra of charged particles produced within the pseudo-rapidity range of η= − 0.36 to + 1.0 have been measured in pp collisions at √s=0.3, 0.54, 1.0, and 1.8 TeV. The spectra are presented as a function of event charged multiplicity within the range −3.25<η<3.25. We found that the slope in the low pt region is independent of center-of-mass energy and multiplicity while the slope at the high pt region shows a strong energy and multiplicity dependence.

\sqrt{s}

Abstract The D 0 →K − π + branching fraction has been measured by tagging a sample of D ∗+ → D 0 π + decays, independent of the D 0 decay mode. The D ∗ mesons were obtained in e + e − annihilations at √ s =29 GeV using data obtained with the HRS detector at PEP. The result iss Br(D 0 →K − π + ) = 4.5±0.8±0.5%.

= 0.3-TeV to 1.8-TeV

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.

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

Data collected with the High Resolution Spectrometer at PEP, corresponding to an integrated luminosity of 200 pb- 1 ofe+e annihilation at 29 GeV, were used to measure the mean hfetlme of hadrons containing the bottom quark. The hfetlme was determined using the impact parameter method on events containing a high-transverse-momentum electron The result, based on a sample of 301 events, is vB = 102~039042 ps, where the Indicated errors include both statistics and systematlcs In the context of the standard model, the lifetime of hadrons containing a bottom quark is determined by the electroweak coupling between the b and the c and u quarks. In the Kobayashi-Maskaw a scheme, the lifetime constrains the values of the matrix elements [ Vbc [ and ] Vbu [ [ 11. This letter presents a measurement of the lifetime of a mixture of hadrons containing the b-quark. The data sample consists of e+e---}bb annihilations at x/~=29 GeV, tagged by a high-PT electron coming from the semileptonic decay of the b-quark. Two different analysis techniques are used, but the quoted result is based on a maximum likelihood fit to the measured impact parameter distribution. A detailed description of the High Resolution Spectrometer can be found elsewhere [2]. For this analysis, the tracking system is essential. It consists