Using the CLEO detector at the Cornell Electron-positron Storage Ring, we have measured the scaled momentum spectra, dsigma/dx_p, and the inclusive production cross sections of the charm mesons D+, D0, D*+, and D*0 in e+e- annihilation at about 10.5 GeV center of mass energy, excluding the decay products of B mesons. The statistical accuracy and momentum resolution are superior to previous measurements at this energy.
Total cross sections for D production from the various decay modes. The data are fully corrected for detection efficiency and decay branching ratios. The second DSYS error is the error due to the uncertainty in the branching ratio.
Differential cross sections for D+ production from the (K- PI+ PI+) decay mode.
Differential cross sections for D0 production from the (K- PI+) decay mode.
The interaction of virtual photons is investigated using the reaction e+e- -> e+e- hadrons based on data taken by the OPAL experiment at e+e- centre-of-mass energies sqrt(s_ee)=189-209 GeV, for W>5 GeV and at an average Q^2 of 17.9 GeV^2. The measured cross-sections are compared to predictions of the Quark Parton Model (QPM), to the Leading Order QCD Monte Carlo model PHOJET to the NLO prediction for the reaction e+e- -> e+e-qqbar, and to BFKL calculations. PHOJET, NLO e+e- -> e+e-qqbar, and QPM describe the data reasonably well, whereas the cross-section predicted by a Leading Order BFKL calculation is too large.
Total cross section in the given phase space and assuming ALPHA = 1/137.
Differential cross section as a function of X where X is the maximum value of X1 or X2, the upper and lower vertex values.
Differential cross section as a function of Q**2 where Q**2 is the maximum value of Q1**2 or Q2**2, the upper and lower vertex values.
Measurements are reported of inclusivef2(1270) andf0(975) production in γp, π±p andK±p collisions at photon beam energies of 65 to 175 GeV and hadron beam energies of 80 and 140 GeV. Thef2 andf0 mesons were found at masses of 1.250 GeV and 0.961 GeV respectively. Inclusivef2 production at lowxF was found to have a similarpT dependence for each beam type, whereas an additional pion-exchange contribution was found for production by pions at highxF. Cross sections are compared with those for ρ0 production and give no indication of a non-q\(\bar q\) component in eitherf-meson state.
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Using the ARGUS detector at thee+e− storage ring DORIS II at DESY, we have measured the inclusive production ofD0,D+ andD*(2010)+ mesons inB decays and in nonresonante+e− annihilation around 10.6 GeV. The inclusive branching ratios forB decays toD0,D+ andD*+ mesons are found to be (52.2±8.2±3.5)%, (27.2±6.3±3.5)% and (34.8±6.0±3.5)% respectively. Thus,D0 andD+ production account for about 70% of the charm produced inB decays, neglectingb→u contributions to the total width. The production cross sections and momentum spectra for continuume+e− annihilation are also presented.
Non-resonant inclusive cross sections.
Non-resonant inclusive cross sections.
Non-resonant inclusive cross sections.
We report results on inclusive production of the charmed baryon Λc+ from e+e− annihilations at s=10.5 GeV. Measurements are presented of the inclusive cross section times branching fraction for the continuum production of Λc+ as observed in six different decay modes, and of a new, improved value of the Λc+ mass. The inclusive cross section times the branching fraction into pK−π+ is measured to be 10.0±1.5±1.5 pb summed over all xp. The branching fractions of Λc+ into pK¯0, pK¯0π+π−, Λπ+, Λπ+π−π+, and Ξ−K+π+ relative to that into pK−π+ are measured to be 0.44±0.07±0.05, 0.43±0.12±0.04, 0.18±0.03±0.03, 0.65±0.11±0.12, and 0.15±0.04±0.03, respectively. The Λc+ mass is measured to be 2284.7±0.6±0.7 MeV/c2. The measured momentum distributions for continuum production of Λc+ are compared to analytical fragmentation functions and to other measurements.
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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.
Using the ARGUS detector at the DORIS II storage ring at DESY, we have observed a charmed meson of mass (2455±3±5) MeV/c2, decaying to D + π − . The natural width of this state is determined to be (15 +13+5 −10−10 ) MeV c 2 . The fragmentation function is hard, as expected for a leading charmed particle from nonresonant e + e − annihilation. Analysis of the decay angular distribution supports the hypothesis that the observed state is an L =1 excited charmed meson with spin-parity 2 + .
Corrected to zero momentum using fragmentation function of Peterson et al., PR D29 (83) 105.
Data read from graph.
We report results on the differential and total cross sections for inclusive production of the charmed particles D*+, D*0, D0, D+, Ds, and Λc in e+e− annihilations at √s=10.55 GeV. Widely used quark fragmentation models are discussed and compared with the measured charmed-particle momentum distributions. This comparison, as well as that with measurements at other center-of-mass energies, shows the need to take QCD corrections into account and their importance for a correct interpretation of the model parameters. The observed rate of D0 and D+ production is compared to the expected total charm production cross section. We measure the probability of a charmed meson being produced as a vector meson and the D*+ decay branching fraction into D0π+.
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The production cross sections for the Λ, Σ0, Ξ−, Σ0 (1385), Ξ0 (1530) and Ω− hyperons have been measured, both in the continuum and in direct ϒ decays. Baryon rates in direct ϒ decays are enhanced by a factor of 2.5 or more compared to the continuum. Such a large baryon enhancement cannot be explained by standard fragmentation models. The strangeness suppression for baryons and mesons turns out to be the same. A strong suppression of spin 3/2 states is observed.
Hyperon rates per multihadronic event in direct UPSILON decays.
Hyperon rates per multihadronic event in the continuum.
LAMBDA spectrum (1/SIG(had))*D(SIG)/D(X) for UPSILON (1S) direct decays, with X = P/Pmax.
We have observed Λc baryons in nonresonant e+e− annihilation at energies around s=10.5 GeV through their decay to Λπ+π+π−. We measure the branching fraction to be (2.8 ± 0.7 ± 1.1)%. The momentum spectrum of the Λc is similar to that of charmed mesons, providing a constraint on models of charmed-quark hadronization.
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Data are extrapolated over whole x range using the 'Peterson' formula.
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