CHARGED KAON PRODUCTION IN TAU-DECAYS AT LEP

Kaon production in one prong tau decays has been studied using data collected with the DELPHI detector at the LEP collider. Charged kaons were identified over a large momentum range by the DELPHI barrel Ring Imaging Cherenkov detector. The following branching ratios have been determined: BR(tau –> Knu(T)) = (0.85 +/- 0.18) %, BR(tau –> Knu(tau) greater-than-or-equal-to 0 neutrals) = (1.54 +/- 0.24) %, BR(tau –> Knu(tau) greater-than-or-equal-to 1 neutrals) = (0.69 +/- 0.25) %. The result for the exclusive branching ratio is consistent with the Standard Model prediction based on tau - mu - e universality. In addition, tau decay into K*- was studied in the channel K*- –> K- pi0. The result BR(tau –> K*-nu(tau)) x BR(K*- –> K- pi0) = (0.57 +/- 0.23)% was obtained

Measurement of the rate of b(b)over-bar-b(b)over-bar events in hadronic Z decays and the extraction of the gluon splitting into b(b)over-bar

The rate Z –> b (b) over bar b (b) over bar was measured using about 2 x 10(6) hadronic decays collected by the DELPHI experiment in 1994 and 1995. Events were forced into 3-jets with y(min) > 0.06 and a b-tag was required for every jet. The rate was measured to be: R-4b = BR(Z –> b (b) over bar b (b) over bar/BR(Z –> hadrons), = (6.0 +/- 1.9(stat.) +/- 1.4(syst.)) x 10(-4) where the invariant mass of every b (b) over bar system is above twice the b quark mass. Using the value of R-4b the probability of secondary production of a b (b) over bar pair from a gluon per hadronic Z decay, g(bb), was extracted and found to be: g(bb) = (3.3 +/- 1.0(stat.) +/- 0.8(syst.)) x 10(-3). (C) 1999 Published by Elsevier Science B.V. All rights reserved