We have studied inclusive KS, Λ, and Λ¯ photoproduction over the ranges 40
No description provided.
The charged particle multiplicities of the quark and gluon jets in the three-fold symmetric e + e − → q q g 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 9 4 naively expected from the ration of the gluon-to-quark color charges.
Mean jet charged particle interpretations for gluon and quark jets as described above.
This Letter reports a search for the production by e+e− annihilation of a single photon accompanied by particles that interact only weakly in matter. The search was performed at the SLAC e+e− storage ring PEP (√s =29 GeV) with a new detector, ASP. No unexpected signal was observed. The limit Nν<14 (90% C.L.) is placed on the number of light neutrino species, and the mass of scalar electrons predicted by theories of supersymmetry is constrained to mẽ>51 GeV/c2 (90% C.L.) for mγ̃=0 and degenerate ẽ mass states.
No description provided.
The ratio of differential cross sections for the reactions e + e − → γγ and e + e − → e + e − is measured at s = 29 GeV in the central polar angle region, |cos θ | < 0.55, and compared to the same ratio calculated by QED to order α 3 . The ratio of these ratios, integrated over this angular region, is 1.007±0.009±0.008, demonstrating excellent agreement between theory and experiment. The 95% confidence limits on the QED cut-off parameters for the γγ final state are Λ + > 59 GeV and Λ - > 59 GeV.
No description provided.
Results are reported on a high statistics study of Bhabha scattering at 29 GeV in the polar angle region, |cos θ | < 0.55. The data are consistent with the standard model, and measure vector and axial-vector coupling constants of g v 2 = 0.03 ± 0.09 and g a 2 = 0.46±0.14. Limits on the QED-cutoff parameters are Λ + > 154 GeV and Λ - > 220 GeV. Lower limits on scale parameters of composite models are in the range 0.9–2.8 TeV. The partial width of a hypothetical spin-zero boson decaying to e + e − has an upper limit which varies from 6 to 57 MeV corresponding to a boson mass in the range 45–80 GeV/ c 2 .
No description provided.
No description provided.
Angular distributions of the spin-correlation parameters Asl and All for the reaction pp→π+d have been measured at pion center-of-mass angles 40°≤θπ+*≤130° at incident energies of 500, 650, and 800 MeV. Additional measurements of All were made at 600, 700, and 750 MeV. The results of the experiment are compared with the predictions of several unified coupled-channel calculations and partial-wave analyses. While the latest partial-wave analyses were found to fit the data reasonably well, all except one of the various model predictions not only do not fit the data well, but also tend to be in disagreement with each other. The data show no clear sign of a need for proposed dibaryon resonances.
No description provided.
No description provided.
No description provided.
The multiplicities per event of π ± and K ± are measured separately for e + e - annihilation into c c , b b , and light quark pairs at E cm=29 GeV. The K ± multiplicity is higher for heavy quark events than for light quark events. The π ± multiplicity and the π ± scaled differential cross section at low x = E beam/ E beam are found to be higher for b b events than for other events.
Numerical values requested from authors. Data given separately for (b bbar), (c cbar) and light quark jets.
Measured multiplicities for (b bbar) jets.
Measured multiplicities for (c cbar) jets.
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 .
KNO charged multiplicity distributions for the Inclusive Data Sample. The numerical values are calculated from the multiplicity distributions given in Derrick et al., PR D34,3304.
Folded rapidity distribution measured along the thrust axis of the event. Errors are dominated by systematics. All charged particles are assigned the pion mass.
KNO charged multiplicity distribution for the Two Jet Data Sample. The numerical values are calculated from the multiplicity distributions given in Derrick et al., PR D34,3304.
This paper presents measurements of the inclusive production cross sections of Λ baryons in e+e− annihilations at s=29 GeV. The data sample corresponds to an integrated luminosity of 256 pb−1 collected with the High-Resolution Spectrometer at the SLAC storage ring PEP. Comparisons are made to the predictions of the Lund model. The data are well described with use of a strange-diquark suppression parameter, (usud)(sd), of 0.89 ± 0.10−0.16+0.56, and the measured Λc→Λ+X branching ratio of (23 ± 10)%.
No description provided.
Rapidity relative to thrust axis.
Corrected for unobserved moment regions.
We report on the first search with virtual photon-photon collisions for narrow, neutral resonances with even C parity in the mass range 4.5
No description provided.
Forum