Der neutrale Kei Zerfall ist experimentell wesentlich weniger genau untersucht als der entsprechende K± Zerfall (bei letzterem wurden bisher einige zehntausend Er- eignisse beobachtet, bei ersterem nicht einmal tausend). Allerdings hat er einige interessante physikalische Eigenschaften: aus Symmetriegründen ist der ansonsten dominierende Formfaktor F stark unterdrückt, wodurch sich die Pionen in einem (fast) reinem p-Zustand befinden, während beim K*t Zerfall ein Mischzustand vorliegt. Weiters stellt sich im Rahmen chiraler Störungstheorie eine empfindli- che Abhängigkeit des Verzweigungsverhältnisses von dem nur ungenau bekannten Kopplungsparameter L3 heraus, was den neutralen Ket Zerfall zur Messung dieses Parameters prädestiniert. Der Vortrag berichtet über theoretische Untersuchungen sowie erste experimentel- le Ergebnisse der Kti Analyse. Da das im Mai veröffentlichte neue Ergebnis der Re^/e) Messung eine grosse Resonanz gefunden hat, wird auch dieses kommen- tiert werden. •) Gefördert aus Mitteln des BMWV: GZ 616.360/2-W und GZ
616.363/2-VIII, sowie des Fonds zur Förderung der wissenschaftlichen Forschung: P-8929-PHY. The Virtual Black Hole in 2D Quantum Gravity D. Grumiller1, W. Kummer1, D.V. Vassilevich2, i 'Institut für Theoretische Physik, TU Wien, Wiedner Hauptstrasse 8-10, j A-1040 Wien; 2Institut für Theoretische Physik, Universität Leipzig, Augu- j stusplatz 10, D-04109 Leipzig > As shown recently 2d quantum gravity theories — including spherically reduced ~H Einstein-gravity — after an exact path integral of its geometric part can be treated ^ perturbatively in the loops of (scalar) matter. Obviously the classical mechanism of O black hole formation should be contained in the tree approximation of the theory. ~ This is shown to be the case for the scattering of two scalars through an interme- —L diate state which by its effective black hole mass is identified as a "Virtual black •£* hole". The present discussion includes minimally and non-minimally coupled sca- lars. For massive minimally coupled scalars and massless non-minimally coupled scalars a finite S-matrix element is obtained. Search for the Quark-Gluon-Plasma in the NA60 experiment at the SPS/CERN H. Wöhri CERN/EP > The study of high energy heavy ion collisions is presently in a very interesting pha- —I se. Among the most exciting observations made by the SPS experiments at CERN ^ are the NA50 measurements on the centrality dependence of the J/tp suppression O O O ->J 133 O pattern and on the enhancement of the intermediate mass dimuon production, a possible indication of thermal dimuons. NA60, a new SPS experiment, will take da- ta with proton and heavy ion beams between 2001 and 2003, extending the NA50 physics program by means of two new silicon detectors placed in the target regi- on: a beam tracker and a silicon tracking telescope. This vertex spectrometer will enable NA60 to study the production of prompt dimuons, with vastly improved mass resolution, and of muons originating from the decay of charmed mesons, by measuring the impact parameter of the muon tracks. NA60 will study the pattern of J/V' and 4>' production in collisions of Indium nuclei, hopefully confirming that the observations done with Pb-Pb collisions signal the formation of a deconfined quark-gluon phase at SPS energies, and providing fundamental information on the physical mechanisms driving the phase transition. NA60 will also clarify the origin of the dimuon excess seen in the intermediate mass region, maybe due to ther- mal dimuon production, and measure the yield of charmed mesons produced in nuclear collisions. In this talk, I will explain the NA60 detector concept, describe the detectors (including results from feasibility tests), and will present the physics performance capability of the experiment.
Effects of Inner Detector Misalignment and Inefficiency on the |s_ B-physics Trigger of the ATLAS Experiment at LHC h- B. Epp, V.M. Ghete, E. Kneringer, D. Kuhn, A. Nairz 2 Institut für Experimentalphysik, Technikerstraße 25, A-6020 Innsbruck O The ATLAS B-physics trigger relies on good quality track reconstruction, both in ^3" terms of efficiency and track parameter resolution. It is important for the trigger |_ to be robust with respect to the effects of detector misalignment and inefficiency. <£ The impact of misalignment and inefficiency in the pixel and the silicon tracker de- tectors on the efficiency of the level-2 B-trigger for the channel D, -»
Hadronic-Track Parametrization for Fast Simulation of the AT- LAS Experiment at LHC B. Epp, V.M. Ghete, E. Kneringer, D. Kuhn, A. Nairz „ Institut für Experimentalphysik, Technikerstraße 25, A-6020 Innsbruck fs_ A new parametrization for fast simulation of hadronic tracks in the ATLAS Inner O Detector is presented. The parametrization is applicable to both prompt tracks Q (i.e., tracks coming from the interaction point) and tracks with finite production ]5 radius, e.g., pions from Kg -> n+*~ decays. The presentation includes general U^ issues, details on the extraction of the parameters from data obtained with full <£ detector simulation and performance checks.
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