出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：A very precise determination of Vus can be obtained from the semi-inclusive hadronic decay
width of the t lepton into final states with strangeness. The ratio of the Cabibbo-suppressed and
Cabibbo-allowed t decay widths directly measures (Vus=Vud)2, up to very small SU(3)-breaking
corrections which can be theoretically estimated with the needed accuracy. Together with previous
LEP and CLEO data, the recent measurements by Babar and Belle of some Cabibbo-suppressed
t decays imply Vus = 0:21650:0026exp0:0005th, which is already competitive with the standard
extraction from Kl3 decays. The uncertainty is largely dominated by experimental errors and
should be easily reduced with the high statistics of the B factories, providing the most accurate
determination of this parameter. A 1% experimental precision on the Cabibbo-suppressed t decay
width would translate into a 0.6% uncertainty on Vus.
