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We present an analysis of the m 2 s-corrections to Cabibbo-suppressed τ lepton decays employing contour improved resummation within an effective scheme which is an essential new feature as compared to previous analyses. The whole perturbative QCD dynamics of the τ-system is described by the β-function of the effective coupling constant and by two(More)
Two methods are compared that are used in path integral simulations. Both methods aim to achieve faster convergence to the quantum limit than the so-called primitive algorithm (PA). One method, originally proposed by Taka-hashi and Imada, is based on a higher-order approximation (HOA) of the quantum mechanical density operator. The other method is based(More)
Discrete sine-Gordon (SG) chains are studied with path-integral molecular dynamics. Chains commensurate with the substrate show the transition from pinning to quantum creep at bead masses slightly larger than in the continuous SG model. Within the creep regime, a field-driven transition from creep to complete depinning is identified. The effects of disorder(More)
The spectral density of quantum mechanical Frenkel Kontorova chains moving in disordered, external potentials is investigated by means of path-integral molecular dynamics. If the second moment of the embedding potential is well defined (roughness exponent), there is one regime in which the chain is pinned (large masses of chain particles) and one in which(More)
We extract a numerical value for the strong coupling constant α s from the τ lepton decay rate into nonstrange particles. A new feature of our analysis is its renormalization scheme invariance. We obtain α s (M τ) = 0.3184 ± 0.0060 exp in the MS scheme which corresponds to α s (M Z) = 0.1177 ± 0.0007 exp ± 0.0006 hq mass. This new numerical value is smaller(More)