Search

The results of the HARP-CDP group on the comparison of Geant4 Monte Carlo predictions versus experimental data are discussed. It is shown that the problems observed by the group are caused by an incorrect implementation of old features at the programming level, and by a lack of the nucleon Fermi motion in the simulation of quasi-elastic scattering. These drawbacks are not due to the physical models used. They do not manifest themselves in the most important applications of the Geant4 toolkit. [ABSTRACT FROM AUTHOR]

The Binary Cascade introduces a novel approach towards intra-nuclear cascade calculations. Like many QMD codes, it uses a detailed 3-dimensional model of the nucleus, and is based exclusively on binary scattering between reaction participants and nucleons within this nuclear model. Like a classical cascade, it uses optical potentials to describe the time evolution of particles passing through the nuclear medium. In the present paper we introduce the model, and investigate its predictive power for hadron spectra in nucleon nuclear reactions final states. [ABSTRACT FROM AUTHOR]

Using the Crystal Ball detector at the ee storage ring DORIS-II, we have searched for the hadronic transitions Υ(2 S)→ηΥ(1 S) and Υ(2 S)→πΥ(1 S) in exclusive decays where the Υ(1 S) decays into an ee or a µ µ pair and the η and π are detected by their decay modes η→γγ, η→ γγ and π→ γγ. From the number of observed events we derive, after consideration of possible background sources, upper limits on the branching ratios B(Υ(2 S)→ηΥ(1 S))<0.7% and B(Υ(2S)→πΥ(1 S))<0.8% at the 90% confidence level. [ABSTRACT FROM AUTHOR]

A search for the decays γ→ρπ, γ→ J/ψ X and γ→γ a (where X is undetermined and a is an axion) has been completed using the LENA detector at the DORIS storage ring. No evidence for any of these processes was found. For these decay modes we set branching fraction upper limits (90% C.L.) of 2.1×10, 2.0×10 and 9.1×10, respectively. [ABSTRACT FROM AUTHOR]

The ration R=σ( e e→hadrons)/σ( e e→ µ µ) was measured with the LENA detector at DORIS in a scan between 7.40 and 7.48 GeV and between 8.67 and 9.43 GeV center of mass energies. Corrected for QED radiative effects, R is found to be constant with an average value of R=3.37 ±0.06±0.23. No narrow resonances with Γ( Γ/ Γ)⊗0.30 keV (95% C.L.) and no steps have been observed. Based on this value of R, revised values for υ(1S) resonance parameters are presented. [ABSTRACT FROM AUTHOR]

Charged hadron production in e e annihilation is studied in the 7 to 10 GeV CM energy region and at the Υ (9.46) and Υ′ (10.01) resonances with the LENA detector at DORIS. The statistical moments of the charged multiplicities are studied. The data show KNO scaling behaviour and suggest the presence of long range correlations. An average charged multiplicityrise of Δ n(Υ)=0.55±0.19 and Δ n(Υ′)=1.26±0.29 over the continuum is observed for the Υ and Υ′ direct decays. The jet structure of the Υ and Υ′ direct decays is investigated using the charged particles. The polar angular distributions of the jet axis behave like 1+α( T) cosθ with 〈α( T)〉=0.7±0.3 and 〈α( T)〉=0.6±0.4. The 〈α( T)〉 value is in agreement with the QCD vector gluon assignment and excludes scalar gluons by more than four standard deviations. [ABSTRACT FROM AUTHOR]

The Crystal Ball detector at the e e storage ring DORIS II has been used to analyze exclusive semileptonic decays of B mesons produced at γ(4 S) energies. The decay B→evD has been observed with a branching ratio of (7.0±1.8±1.4)% using the π°D decay mode of the D. In addition we have searched for the exclusive semileptonic decay B→ e vπ. We find an upper limit on B→ e vπ of 0.22% at the 90% CL. [ABSTRACT FROM AUTHOR]

The Crystal Ball Collaboration has measured the energy spectrum of electrons from semileptonic B meson decays at the e e storage ring DORIS II. Branching ratios and weak mixing angles of the Kobayashi-Maskawa matrix are determined using several models for the hadronic matrix elements. We obtain the branching ratio for semileptonic. B decays to charmed states BR( B→evX)=(11.7±0.4±1.0)%. Our result for the corresponding Kobayashi-Maskawa matrix element is | V|=0.052±0.006. The model dependence of both results is included in the error. We have not observed semileptonic B decays to non-charmed mesons. Analyzing the measured electron spectrum above 2.4 GeV, where no b→c decays contribute, we find BR( B→evX)/ BR( B→evX)<6.5% at the 90% confidence level. This corresponds to an upper limit | V/ V|<0.21. [ABSTRACT FROM AUTHOR]