Top quark physics at a next e"+e"- linear collider Experimental considerations

The prospects of an e"+e"- Linear Collider with 500 GeV energy for precision measurements in the top quark sector are discussed. Measurements of the total cross section, the top quark momentum distribution and the forward-backward charge asymmetry in the vicinity of the t anti t production threshold yield a precise determination of the top quark mass and the strong coupling constant, #alpha#_S. The measurements are also sensitive to the decay width, and to the strength of the top quark/Higgs boson coupling. Above threshold, the top quark mass can be reconstructed from the t anti t final state. From a detailed helicity analysis, the form factors at the production and decay vertices can be extracted with high accuracy, and anomalous couplings can be searched for. Due to the high top quark mass, its decay offers a natural place to look for non-standard final states, in particular through decay channels predicted by the minimal supersymmetric model. The detection of rare decays involving the t- anti t-H"0 vertex is of particular interest since it provides perhaps a unique opportunity to observe the top quark Yukawa coupling directly. In summary, the Next e"+e"- Linear Collider will provide us with a large variety of measurements of top quark properties. These will be compared to standard model predictions and possible deviations interpreted in terms of new physics. (orig.)SIGLEAvailable from TIB Hannover: RO 6224(1993,6) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman