Final states with charged kaons in three-prong tau decays are studied by exploiting the particle identification from the dE/dx measurement. The results are based on a sample of about 1.6 x 10(5) detected tau pairs collected with the ALEPH detector between 1991 and 1995 around the Z peak. The following branching ratios have been measured: B(tau(-) --> K(-)K(+)pi(-)nu(tau)) = (1.63 +/- 0.21 +/- 0.17) x 10(-3), B(tau(-) --> K(-)pi(+)pi(-)nu(tau)) = (2.14 +/- 0.37 +/- 0.29) x 10(-3), B(tau(-) --> K(-)K(+)pi(-)pi(0) nu(tau)) = (0.75 +/- 0.29 +/- 0.15) x 10(-3), and B(tau(-) --> K(-)pi(+)pi(-)pi(0) nu(tau)) = (0.61 +/- 0.39 +/- 0.18) x 10(-3). The first two measurements are more precise than the current world averages, while the last two channels are investigated for the first time. The 95% C.L. upper limit on the branching ratio for the decay tau(-) --> K(-)K(+)K(-)nu(tau) is 0.19 x 10(-3). A study of intermediate states occurring in the K(-)K(+)pi(-)nu(tau), and K(-)pi(+)pi(-)nu(tau), decays is also presented. RI ANTONELLI, ANTONELLA/C-6238-2011; Jones, Roger/H-5578-2011; Passalacqua, Luca/F-5127-2011; Murtas, Fabrizio/B-5729-2012; O'Shea, Val/G-1279-2010; St.Denis, Richard/C-8997-2012; Ferrante, Isidoro/F-1017-2012; Sanchez, Federico/F-5809-2012
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