Abstract :
The hadronic decay of the top quark t → bW+ → bq1q2 is analyzed in the rest system of the W. The angular distribution between the heavy quarks and the thrust direction gives information about the amount of longitudinal and transverse W′s in the decay. Higher order QCD corrections are calculated and their structure is elucidated in some detail. It is argued that this observable will be an ideal tool to study top quark properties at Tevatron and LHC.
