STRING CONTRIBUTIONS IN 3D Z2 AND Z5 GAUGE-MODELS

We describe a high precision Monte Carlo test on Z2 and Z5 gauge models in 3D. Wilson loops of size 2 less-than-or-equal-to R, T less-than-or-equal-to 12 are measured and values of the string tension sigma are extracted. These values fulfil asymptotic scaling if and only if the string contributions, namely the quantum fluctuations of the surfaces bordered by Wilson loops, are properly taken into account. As a byproduct of our analysis we find the signature of the finite thickness of these flux tubes.