Measurement of the strong coupling constant alpha s at the Z0 resonance using modified jet mass difference.

A modified jet mass difference (thrust criterion) technique is used to extract the value of alpha(s)(M(Z0)2). This new technique suppresses fragmentation uncertainty, reducing the overall systematic error. Based on this method and using results from two experiments at the CERN e+e- collider LEP, we determine alpha(s)(M(Z0)2) = 0.127 +/- 0.004, where the errors have been added in quadrature.