Computation of the running coupling in the SU(2) Yang-Mills theory

A finite-size scaling technique is applied to the SU(2) gauge theory (without matter fields) to compute a non-perturbatively defined running coupling α(q) for a range of momenta q given in units of the string tension K. We find that already at rather low q, the evolution of α(q) is well described by the 2-loop approximation to the Callan-Symanzik β-function. At the highest momentum reached, q=20x√K, we obtain αsub(anti Manti S)(q)=0.187±0.005±0.009 for the running coupling in the anti Manti S scheme of dimensional regularization. (orig.)