Search

16 pp. (2001).

13 pp. (2000).

5 pp. (2000)., The experimental sensitivity of the reaction $e^+ e^- \to b \bar{b}\to b\bar{b}A$has been studied with a full-statistics background simulation for sqrt(s) = 500 GeV and L = 500 fb$^-1$. The simulation is based on a fast and realistic simulation of a TESLA detector. For the first time this reaction has been analysed for a future linear collider and we show that a signal could be observed. A significant signal over background is achieved by the application of an Iterative Discriminant Analysis (IDA). For a signal production cross section of only 2 fb, which is expected for a Higgs boson mass of 100 GeV and $\tan(\beta) = 50$, we achieve 100 signal over 100 background events, and obtain for a $\tan(\beta)$ measurement: $\Delta(\tan(\beta)) / \tan(\beta) = 0.07$. This measurement requires a high-luminosity future collider as proposed in the TESLA project.

6 pp. (1999)., The calculation of the tree-level QCD processes $e^+e^- \to qqgggg$, $qqqqgg$ and $qqqqqq$ has recently been accomplished. We highlight here the relevance of such reactions for some of the physics at future electron-positron linear accelerators.

14 pp. (1999).

11 pp. (1995)., The measurement of the forward-backward asymmetries of heavy quarks provides one of the most precise determinations of $\sin~2\theta_W$ in $Z$ decays. We discuss in detail the one--loop QCD radiative corrections to these asymmetries. Results are given for single heavy--quark jet asymmetries and asymmetries of the thrust axis, as well as for heavy--quark two--jet final states.}

24 pp. (1991)., We have measured the cross section and $Q^2$-dependence of the reaction γγ→ multihadrons, using the CELLO detector at DESY, for visible final-state masses between 4 and 9 GeV. The data are well fitted by an incoherent sum of Generalised Vector Meson Dominance and Quark Parton Model terms, but at lowQ2 require the addition of a third component which resembles the QPM but is less two-jet-like. With and without this term, the GVDM cross section atQ2=0 is found to be 200±20 and 250±25 nb, respectively.

107 pp. (1981).

(1983). doi:10.1103/PhysRevLett.51.443, The results of a high-statistics study of inclusive muon spectra at PETRA are reported. Improved mass limits have been obtained for heavy quarks, heavy leptons, and charged Higgs particles. It is shown that the fragmentation properties of b quarks and c quarks are different, with the mean fragmentation variables 〈zb〉=0.75±0.03±0.06, 〈zc〉=0.46±0.02±0.05 and the average semileptonic branching ratio for the B and C hadrons R(B)=(10.5±1.5±1.3)%, R(C)=(11.5±1.0±1.7)%.

Physical review letters 43(12), 830 - 833 (1979). doi:10.1103/PhysRevLett.43.830, We report the analysis of the spatial energy distribution of data for e+e−→hadrons obtained with the MARK-J detector at PETRA. We define the quantity 'oblateness' to describe the flat shape of the energy configuration and the three-jet structure which is unambiguously observed for the first time. Our data can be explained by quantum chromodynamic predictions for the production of quark-antiquark pairs accompanied by hard noncollinear gluons., Published by APS, College Park, Md.

9 pp. (1980)., Jets in e+e− annihilation are discussed in the context of perturbative Quantum Chromodynamics. Topics discussed include higher twist contribution, effects of quark masses and fragmentation on the 3 and 4 jet rates and some distributions bearing on the experimental verification of 4 jet events at the PETRA/PEP energies.

100 pp. (1980).

(1980). doi:10.1007/BF01588839, We discuss the angular asymmetries of 3-jet events ine+e− annihilation, originating from hard gluon bremsstrahlung off quarks. Lepton beam polarization helps to disentangle the various helicity components of the bremsstrahlung cross section. They are sensitive to the spin of the radiated quantum but are otherwise parameter-free.

7 pp. (1979)., The triplicity method was used to search for triple jets in the decay of T(9.46) into charged and neutral hadrons as an indication of the 3-gluon decay of the T. A comparison of the results with phase space, qij and 3-gluon predictions shows that the data is best described by a 3-gluon decay model.

25 pp. (1979)., Discusses the progress in e/sup +/e/sup -/ annihilation at PETRA energies including jets, tau heavy leptons and the separation of two photon events.

7 pp. (1981).

(1984). doi:10.1007/BF01577037, We report results for the three-jet cross section to order αs2 using a jet resolution criterion depending on the jet mass and study the sum of three-and four-jet cross sections inO(αs2) as a function of the resolution parameters in order to obtain the limit of infinite resolution.

39 pp. (1982).

54 pp. (1980)., Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies

21 pp. (1981).

7 pp. (1979).

8 pp. (1983).

14 pp. (1981).

138 pp. (1986).

41 pp. (1986).

64 pp. (1981).

30 pp. (1979).

Gluons 28 pp. (1981)., The production of hard noncollinear gluons in short distance processes is disussed, with emphasis on recent results from e+e− interactions. The jet phenomena observed in the e+e− continuum and in Υ decay are consistently described as due to the emission of QCD gluons while alternative explanations fail. The vector and color‐nonsinglet nature of the radiated quanta is directly verified.

(1982). doi:10.1088/0031-8949/25/1B/011, Selected topics of recent experimental results from the high-energy electron-position storage rings are presented. The topics include some of the τ and charm physics from SPEAR, the upsilon physics from DORIS and CESR, and the γγ physics and quark and gluon physics from the PLUTO and TASSO Collaborations at PETRA. Related data from the JADE and MARK J Collaborations at PETRA are discussed in separate papers at this School.

12 pp. (1982).

231 pp. (1983).