The inclusive production of π± andK± mesons and of protons and antiprotons ine+e− annihilations has been measured at 34 GeV and 44 G
We have observed ϱ 0 production in e + e − annihilation to hadrons at high energies. The differential cross section at a centre of mass energy W , of 34 GeV, is presented. In the range 0.2< x < 0.7, we measure 0.33 ± 0.06 (stat.) ± 0.07 (syst.), 0.22 ± 0.06 ± 0.05 and 0.22 ± 0.02 ± 0.05 ϱ 0 /event at W = 14, 22 and 34 GeV respectively.
The process e + e − → π 0 + anything has been measured at c.m. energies of 14 and 34 GeV for π 0 energies between 0.5 and 4 GeV. The ratio of π 0 to π ± production for π momenta between 0.5 and 1.5 GeV/ c is measured to be 2 σ ( π 0 )/ [ σ ( π + ) + σ ( π − )] = 1.3 ± 0.4 (1.2 ± 0.4) at 14 (34) GeV. The scaled cross section ( s / μ )d σ /d x when compared with lower energy (4.9–7.4 GeV) π 0 data indicates a substantial scaling violation.
We present evidence for the production of Ξ· − , Ξ − in e + e − annihilation into hadrons. Our measurements yields: 0.026 ± 0.008 (stat.) ± 0.009 (syst.) Ξ − , Ξ − per hadronic event at W ∼ 34 GeV. Using our previous measurements of Λ, Λ and p, p production we obtain the relative yields (Ξ − , Ξ − /(Λ, Λ = 0.087 ± 0.03 ( stat. ) ± 0.03 ( syst. ) and (Ξ − , Ξ − /( p , p = 0.033 ± 0.011 ( stat. ) ± 0.011 ( syst. ) .
Production of the F meson by e + e − annihilation at high energies has been obsrved in the ϕπ final state with a mass of 1.975 ± 0.009 ± 0.010 GeV and a width consistent with the mass resolution. The yield of F production times branching ratio relative to μ pair production is R F ( x ⩾ 0.3) B (F ± → ϕπ ± ) = 0.061 ± 0.012 ± 0.018.
Inclusive K 0 -production has been measured in e + e - annihilation at a center of mass energy of about W = 30 GeV. The ratio of K 0 + K 0 production to μ + μ - production is R K 0 = 5.6 ± 1.1 (statist. error) ± 0.8 (system.error) This value is about a factor of three higher than R K 0 at W = 7 GeV. The cross sections ( s / β ) d σ /d x is consistent with a scaling behaviour.
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.
We have observed e + e − hadrons at C.M. energies of 13 GeV and 17 GeV at PETRA using the TASSO detector. We find R (13 GeV) = 5.6 ± 0.7 and R (17 GeV) = 4.0 ± 0.7. The additional systematic uncertainty is 20%. Comparing inclusive charged hadron spectra we observe scaling between 5 GeV and 17 GeV for x = p / p beam > 0.2; however the 13 GeV cross section is above the 17 GeV cross section for smaller x . This may be due to copious bb̄ production. The events become increasingly jet like at high energies as evidenced by a shrinking sphericity distribution with increasing energy.
Jet properties ine+e− annihilation at center of mass energies of 14, 22, 35 and 43.7 GeV were studied with the data collected in the TASSO detector at PETRA, using the same evaluation procedures for all the energies. The total hadronic cross section ratio for the center of mass energy interval 39–47 GeV was determined to be ℛ=4.11±0.05 (stat)±0.18(syst.) at\(\langle \sqrt s \rangle= 43 - 7\) GeV. Corrected distributions of global shape variables are presented as well as the inclusive charged particle distributions for scaled momentum and transverse momentum. The center of mass energy evolution of the average sphericity, thrust, aplanarity and particle momentum is shown.
The full TASSO data have been used to study the inclusive production of strange mesons ine+e− annihilations. Differential and total cross sections have been measured in the centre of mass energy range 14 to 44 GeV forK0,\(\bar K^0\) and 34.5 to 44 GeV forK*± (892). We have investigated the strange meson production properties in jets by studying the rapidity andpt2 distributions as well as the evolution of the multiplicities as a function of the event sphericity. We find no evidence that the strange meson yields increase with increasing sphericity faster than the total charged multiplicity.
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