Using a data sample of 1475000 Z --> q (q) over bar(gamma) events collected during 1993 with the L3 detector at LEP, we have studied the purely leptonic decays of heavy flavour mesons, D-s(-) --> tau(-)(v) over bar(tau) and B- --> tau(-)(v) over bar(tau). A signal is observed in the invariant mass distribution M(gamma D-s(-)) corresponding to the decay sequence D-s(*-) --> gamma D-s(-), D-s(-) --> tau(-)(v) over bar(tau), tau(-)(v) over bar(tau), tau(-) --> l(-)(v) over bar(l)v(tau). The branching fraction for D-s(-) tau(-) (v) over bar(tau) decays is measured to be B(D-s(-) --> tau(-)(v) over bar(tau)) = 0.074 +/- 0.028(stat) +/- 0.016(syst) +/- 0.018(norm). No signal of B- --> tau-(v) over bar(tau) decays is observed in the data, corresponding to an upper limit on the branching fraction B(B- --> tau(-)(v) over bar(tau)) < 5.7 x 10(-4) at 90% CL. (C) 1997 Elsevier Science B.V.
Measurement of D-s(-)->tau(-)(nu)over-bar(tau) and a new limit for B-->tau(-)(nu)over-bar(tau center dot)
F. Ferroni;
1997-01-01
Abstract
Using a data sample of 1475000 Z --> q (q) over bar(gamma) events collected during 1993 with the L3 detector at LEP, we have studied the purely leptonic decays of heavy flavour mesons, D-s(-) --> tau(-)(v) over bar(tau) and B- --> tau(-)(v) over bar(tau). A signal is observed in the invariant mass distribution M(gamma D-s(-)) corresponding to the decay sequence D-s(*-) --> gamma D-s(-), D-s(-) --> tau(-)(v) over bar(tau), tau(-)(v) over bar(tau), tau(-) --> l(-)(v) over bar(l)v(tau). The branching fraction for D-s(-) tau(-) (v) over bar(tau) decays is measured to be B(D-s(-) --> tau(-)(v) over bar(tau)) = 0.074 +/- 0.028(stat) +/- 0.016(syst) +/- 0.018(norm). No signal of B- --> tau-(v) over bar(tau) decays is observed in the data, corresponding to an upper limit on the branching fraction B(B- --> tau(-)(v) over bar(tau)) < 5.7 x 10(-4) at 90% CL. (C) 1997 Elsevier Science B.V.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
