Measurement of VubV_{ub}

The most recent experimental measurements of the weak mixing angle $V_{ub}$ are summarized. Inclusive and exclusive analysis techniques are described, including a new exclusive analysis by the CLEO collaboration measuring the $B\rightarrow \pi\ell\nu$ branching ratio. Future prospects are discussed.Comment: 7 pages with four postscript figures. LaTeX using revtex. Presented at the 6'th International Symposium on Heavy Flavor Physics, June 1995, Pisa Ital

Determination of the Michel Parameters rho, xi, and delta in tau-Lepton Decays with tau --> rho nu Tags

Using the ARGUS detector at the $e^+ e^-$ storage ring DORIS II, we have measured the Michel parameters $\rho$, $\xi$, and $\xi\delta$ for $\tau^{\pm}\to l^{\pm} \nu\bar\nu$ decays in $\tau$-pair events produced at center of mass energies in the region of the $\Upsilon$ resonances. Using $\tau^\mp \to \rho^\mp \nu$ as spin analyzing tags, we find $\rho_{e}=0.68\pm 0.04 \pm 0.08$, $\xi_{e}= 1.12 \pm 0.20 \pm 0.09$, $\xi\delta_{e}= 0.57 \pm 0.14 \pm 0.07$, $\rho_{\mu}= 0.69 \pm 0.06 \pm 0.08$, $\xi_{\mu}= 1.25 \pm 0.27 \pm 0.14$ and $\xi\delta_{\mu}= 0.72 \pm 0.18 \pm 0.10$. In addition, we report the combined ARGUS results on $\rho$, $\xi$, and $\xi\delta$ using this work und previous measurements.Comment: 10 pages, well formatted postscript can be found at http://pktw06.phy.tu-dresden.de/iktp/pub/desy97-194.p

Experimental momentum spectra of identified hadrons at e+e−e^+e^- colliders compared to QCD calculations

Experimental data on the shape of hadronic momentum spectra are compared to theoretical predictions in the context of calculations in the Modified Leading Log Approximation (MLLA), under the assumption of Local Parton Hadron Duality (LPHD). Considered are experimental measurements at $e^+e^-$-colliders of $\xi_p^*$, the position of the maximum in the distribution of $\xi_p=\log(1/x_p)$, where $x_p=p/p_{beam}$. The parameter $\xi_p^*$ is determined for various hadrons at various centre of mass energies. The dependence on the hadron type poses some interesting questions about the process of hadron-formation. The dependence of $\xi^*_p$ on the centre of mass energy is seen to be described adequately by perturbation theory. A quantitative check of LPHD + MLLA is possible by extracting a value of $\alpha_s$ from an overall fit to the scaling behaviour of $\xi^*_p$.Comment: 9 pages latex, 7 eps figures and total ps fil

Hadronization in Z0 decay

The confinement transition from the quark and gluon degrees of freedom appropriate in perturbation theory to the hadrons observed by real world experiments is poorly understood. In this strongly interacting transition regime we presently rely on models, which to varying degrees reflect possible scenarios for the QCD dynamics. Because of the absence of beam and target remnants, and the clean experimental conditions and high event rates, e+e- annihilation to hadrons at the Z0 provides a unique laboratory, both experimentally and theoretically, for the study of parton hadronization. This review discusses current theoretical understanding of the hadronization of partons, with particular emphasis on models of the non-perturbative phase, as implemented in Monte Carlo simulation programs. Experimental results at LEP and SLC are summarised and considered in the light of the models. Suggestions are given for further measurements which could help to produce more progress in understanding hadronization.Comment: Topical review, to appear in J.Phys.G, 80 page

Pattern Recognition and Event Reconstruction in Particle Physics Experiments

This report reviews methods of pattern recognition and event reconstruction used in modern high energy physics experiments. After a brief introduction into general concepts of particle detectors and statistical evaluation, different approaches in global and local methods of track pattern recognition are reviewed with their typical strengths and shortcomings. The emphasis is then moved to methods which estimate the particle properties from the signals which pattern recognition has associated. Finally, the global reconstruction of the event is briefly addressed.Comment: 101 pages, 58 figure

Measurement of the decay Ds2∗+(2573)→D0K+D_{s2}^{*+} (2573) \to D^0K^+

Using the ARGUS detector at the e+e− storage ring DORIS II at DESY we have measured the parameters of a charmed strange meson D*s2+(2573) decaying into D0K+. The mass of this state was found to be (2574.5±3.3±1.6) MeV/c2. The measured value of its width is (10.4±8.3±3.0) MeV and the product of the production cross section and branching ratio for this channel was determined to be (10.6±4.2−1.2+2.3) pb

Search for exotic decay modes of the Υ\Upsilon(1S)

A search for two exotic decay modes of the ϒ(1S) meson has been made using the ARGUS detector at the e+e− storage ring DORIS II at DESY. The first was ϒ(1S) decays into weakly interacting particles, for which an upper limit of 2.3% at the 90% CL on the branching ratio is found. The second mode was ϒ(1S)→γa, where a is a neutral particle with mass less than 1.5GeV/c2, that either decays inside the detector or is sufficiently long-lived to escape detection. For short-lived particles a decaying into an e+e− pair, upper limits on the BR(ϒ(1S)→γa) of 3.1 × 10− at the 90% CL are found. The upper limit without restriction on the lifetime of a is found to be 1.3 × 10−3. Limits for other decay modes are also given

Physics with ARGUS

The impact of the ARGUS experiment to elementary particle physics is reviewed. More than ten years of data taking has allowed ARGUS to contribute significantly to our understanding of beauty and charmed hadrons, τ Leptons, ϒ mesons, ϒϒ interactions and fragmentation processes. In particular the ARGUS measurements of CKM matrix elements opened up a new window on the Standard Model