Resumen de Measurement of the tau lifetime using the aleph detector
In this thesis a determination of the tau lifetime using the data collected by the aleph detector at cern's lep accelerator is presented. The data were obtained during the 1989 and 1990 curring periods. Two techniques are commonly used to determine the lifetime of particles: measurement of the decay length and measurement of the impact parameters. The latter can be applied to a larger sample of events, thus resulting in smaller statistical errors, and is therefore used here. The values obtained for the lifetime are 286- 18(stat)- 10(syst) fs for 1-1 topology events and 329- 38(stat)-18 (syst) for 1-3 topology events. These values, combined with two additional tau lifetime and branching ratio measurements, also obtained by aleph, give a ratio of the couling constants gt/gu = 0.993 - 0.028, compatible with the hypothesis of leptonic universality.
