über die Verallgemeinerung eines Ergodensatzes von Dunford

Ohne Zusammenfassung     

Search for narrow resonances in e+e− annihilation at petra

We have performed a search for narrow resonances in the center of mass energy range from 29.90 to 31.46 GeV using the e⁺e^? storage ring PETRA at DESY. We present the total cross section for hadron production and an upper limit for resonance production, indicating that no bound state of charge-$\text{2}\text{3}$ quarks exists in this energy range.     

The total hadronic cross section for e+e− annihilation between 3.1 and 4.8 GeV center of mass energy

Using the solenoidal magnetic detector PLUTO, we have measured the total cross section for e⁺e^? annihilation into hadrons. Results are presented for center of mass energies between 3.6 and 4.8 GeV, and in the regions of the $\text{J}\text{ψ}$(3.1) and ψ(3.7) resonances. We also present results for the 2 prong cross section in the energy range 3.6 to 4.8 GeV.     

Charged hadron multiplicities and inclusive π− distributions in inelastic ep scattering

Electroproduction of hadrons is studied in the kinematic region W < 2.8 GeV and 0.3 < Q² < 1.4 GeV² using the DESY streamer chamber. Prong cross sections, charged-particle multiplicities and inclusive π^? distributions are presented. The average charged multiplicity is found to be independent of Q² in the Q² range studied here; however it is lower than in photoproduction. The fraction of forward π^? is found to be significantly less in electroproduction than in photoproduction. The 〈p_⊥²〉 for inclusive π^? is, for all x values, similar to that found in photoproduction.     

Multiplicity distributions in e+e− annihilations at petra energies

Measurements of the charged multiplicities for hadron production in e⁺e^? annihilation in the center of mass energy range 9–32 GeV have been made. The average charged multiplicity has an energy dependence much stronger than ln s and similar to that reported for pp collisions. Quantitative differences are observed in the magnitude of both the average multiplicity 〈n_ch〉 and the dispersion D_ch for e⁺e^? and pp interactions at the same center of mass energy. 〈n_ch〉 and the ratio 〈n_ch/D_ch in e⁺e^? annihilations are significantly larger than in pp collisions and are found to be in overall agreement with QCD predictions. KNO scaling is seen to be satisfied.     

An efficient step size control for continuation methods

In solving a nonlinear equation by the use of a continuation method one of the crucial problems is the choice of the step sizes. We present a model for the total computational cost of a standard numerical continuation process and solve the problem of optimal step size control for this model. Using the theoretical results as a basis, we develop an adaptive step size algorithm for Newton's method. This procedure is computationally inexpensive and it gives quite satisfactory results compared to some other numerical experiments found in the literature.     

Measurement of the f0(1270) polarization in the J/ψ → f0γ decay

The polarization of the f⁰(1270) and ?⁰(770) produced in the J/ψ decays into f⁰γ and ?⁰π⁰ are measured in e⁺e^? collisions at 3.1 GeV. A fit to the f⁰ production and decay angular distributions yields the values A₁/A₀ = 0.6 ± 0.3 and A₂/A₀ = 0.3 _?1.6^+0.6, where A_λ are the f⁰ helicity amplitudes. These results are in good agreement with the values predicted from a QCD two-gluon-exchange model. In addition an upper limit of 2.3 × 10^?4 is obtained for the J/ψ → f′⁰(1514) γ decay branching ratio which implies Γ(J/ψ → f′γ)/Γ(J/ψ → f⁰γ) ? 0.12 ± 0.05.