Quark-Gluon Jet Differences at LEP

A new method to identify the gluon jet in 3-jet ``{\bf Y}'' decays of $Z^0$ is presented. The method is based on differences in particle multiplicity between quark jets and gluon jets, and is more effective than tagging by leptonic decay. An experimental test of the method and its application to a study of the ``string effect'' are proposed. Various jet-finding schemes for 3-jet events are compared.Comment: 11 pages, LaTeX, 4 PostScript figures availble from the author ([email protected]), MSUTH-92-0

A Comparison of the Use of Binary Decision Trees and Neural Networks in Top Quark Detection

The use of neural networks for signal vs.~background discrimination in high-energy physics experiment has been investigated and has compared favorably with the efficiency of traditional kinematic cuts. Recent work in top quark identification produced a neural network that, for a given top quark mass, yielded a higher signal to background ratio in Monte Carlo simulation than a corresponding set of conventional cuts. In this article we discuss another pattern-recognition algorithm, the binary decision tree. We have applied a binary decision tree to top quark identification at the Tevatron and found it to be comparable in performance to the neural network. Furthermore, reservations about the "black box" nature of neural network discriminators do not apply to binary decision trees; a binary decision tree may be reduced to a set of kinematic cuts subject to conventional error analysis.Comment: 14pp. Plain TeX + mtexsis.tex (latter available through 'get mtexsis.tex'.) Two postscript files avail. by emai

Prevention and control of apple scab

Improved prevention and control of apple scab caused by Venturia inaequalis is aimed at without the use of copper containing products in the Repco-project. Substantial progress is made in selection of potential products against summer epidemics. A patent application is made for E73. New effective biocontrol agents are selected to reduce inoculum during winter. The product potassium bicarbonate has shown good efficacy and Repco contributes to the registration of this product in Europe. Earthworms tended to be stimulated to consume apple leaves treated with amino acids or beetpulp, especially when applied fresh under controlled environmental condi-tons

The problem of mutually unbiased bases in dimension 6

We outline a discretization approach to determine the maximal number of mutually unbiased bases in dimension 6. We describe the basic ideas and introduce the most important definitions to tackle this famous open problem which has been open for the last 10 years. Some preliminary results are also listed

Measurements of Lifetimes and a Limit on the Lifetime Difference in the Neutral D-Meson System

Using the large hadroproduced charm sample collected in experiment E791 at Fermilab, we report the first directly measured constraint on the decay-width difference Delta Gamma for the mass eigenstates of the D0-D0bar system. We obtain our result from lifetime measurements of the decays D0 --> K-pi+ and D0 --> K-K+, under the assumption of CP invariance, which implies that the CP eigenstates and the mass eigenstates are the same. The lifetime of D0 --> K-K+ (the CP-even final state is \tau_KK = 0.410 +/- 0.011 +/- 0.006 ps, and the lifetime of D0 --> K-pi+ (an equal mixture of CP-odd and CP-even final states is tau_Kpi = 0.413 +/- 0.003 +/- 0.004 ps. The decay-width difference is Delta Gamma = 2(Gamma_KK - Gamma_Kpi) = 0.04 +/- 0.14 +/- 0.05 ps^-1. We relate these measurements to measurements of mixing in the neutral D-meson system.Comment: 8 pages + 3 figures + 2 table

Searching for a heavy Higgs boson via the H --> l nu jj decay mode at the CERN LHC

The discovery of a heavy Higgs boson with mass up to m_H = 1 TeV at the CERN LHC is possible in the H--> W^+W^- --> l nu jj decay mode. The weak boson scattering signal and backgrounds from t\bar tjj and from W+jets production are analyzed with parton level Monte Carlo programs which are built on full tree level amplitudes for all subprocesses. The use of double jet tagging and the reconstruction of the W invariant mass reduce the combined backgrounds to the same level as the Higgs signal. A central mini-jet veto, which distinguishes the different gluon radiation patterns of the hard processes, further improves the signal to background ratio to about 2.5:1, with a signal cross section of 1 fb. The jet energy asymmetry of the W --> jj decay will give a clear signature of the longitudinal polarization of the W's in the final event sample.Comment: 23 pages (with 7 embedded figures), Revtex, uses epsf.sty. Z-compressed postscript version also available at http://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-1017.ps.Z or at ftp://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-1017.ps.

Enhancing the top signal at Tevatron using Neural Nets

We show that Neural Nets can be useful for top analysis at Tevatron. The main features of $t\bar t$ and background events on a mixed sample are projected in a single output, which controls the efficiency and purity of the $t\bar t$ signal.Comment: 11 pages, 6 figures (not included and available from the authors), Latex, UB-ECM-PF 94/1

Clocking hadronization in relativistic heavy ion collisions with balance functions

A novel state of matter has been hypothesized to exist during the early stage of relativistic heavy ion collisions, with normal hadrons not appearing until several fm/c after the start of the reaction. To test this hypothesis, correlations between charges and their associated anticharges are evaluated with the use of balance functions. It is shown that late-stage hadronization is characterized by tightly correlated charge/anticharge pairs when measured as a function of relative rapidity.Comment: 5 pages, 3 figure

The BLG Theory in Light-Cone Superspace

The light-cone superspace version of the d=3, N=8 superconformal theory of Bagger, Lambert and Gustavsson (BLG) is obtained as a solution to constraints imposed by OSp(2,2|8) superalgebra. The Hamiltonian of the theory is shown to be a quadratic form of the dynamical supersymmetry transformation.Comment: 45 pages, v2: reference added, minor typos corrected, published versio