Previously published and as yet unpublished QCD results obtained with the ALEPH detector at LEP1 are presented. The unprecedented statistics allows detailed studies of both perturbative and non-perturbative aspects of strong interactions to be carried out using hadronic Z and tau decays. The studies presented include precise determinations of the strong coupling constant, tests of its avour independence, tests of the SU(3) gauge structure of QCD, study of coherence eects, and measurements of single-particle inclusive distributions and two-particle correlations for many identied baryons and mesons.

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The fragmentation of b quarks into B mesons is studied with four million hadronic Z decays collected by the ALEPH experiment during the years 1991-1995. A semi-exclusive reconstruction of B --> lvD((*)) decays is performed, by combining lepton candidates with fully reconstructed D((*)) mesons while the neutrino energy is estimated from the missing energy of the event. The mean value of x(B)(wd), the energy of the weakly-decaying B meson normalised to the beam energy, is found to be (x(B)(wd)) = 0.716 +/- 0.006 (stat) +/- 0.006 (syst), using a model-independent method; the corresponding value for the energy of the leading B meson is (x(B)(L)) = 0.736 +/- 0.006 (stat) +/- 0.006 (syst). The reconstructed spectra are compared with different fragmentation models. (C) 2001 Published by Elsevier Science B.V

A search has been performed for the Standard Model Higgs boson in the data sample collected with the ALEPH detector at LEP, at centre-of-mass energies up to 209 GeV. An excess of 3 sigma beyond the background expectation is found, consistent with the production of the Higgs boson with a mass near 114 GeV/c(2). Much of this excess is seen in the four-jet analyses, where three high purity events are selected. (C) 2000 Elsevier Science B.V. All rights reserved

The flavour changing neutral current decay b-->sγ has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged bb¯ events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured to beconsistent with the Standard Model expectation via penguin processes