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Strong Coupling Constant with Flavour Thresholds at Four Loops in the MS-bar Scheme

K. G. Chetyrkin·B. A. Kniehl·M. Steinhauser
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Abstract

We present in analytic form the matching conditions for the strong coupling constant alpha_s^(n_f)(mu) at the flavour thresholds to three loops in the modified minimal-subtraction scheme. Taking into account the recently calculated coefficient beta_3 of the Callan-Symanzik beta function of quantum chromodynamics, we thus derive a four-loop formula for alpha_s^(n_f)(mu) together with appropriate relationships between the asymptotic scale parameters Lambda^(n_f) for different numbers of flavours n_f.

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K. G. Chetyrkin, B. A. Kniehl, M. Steinhauser. 1997-06-20. Strong Coupling Constant with Flavour Thresholds at Four Loops in the MS-bar Scheme. https://doi.org/10.1103/physrevlett.79.2184

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