Determination of ±s from a differential-jet-multiplicity distribution in e+e- collisions at ss =29 and 91 GeV

We measured the differential jet-multiplicity distribution in e+e- annihilation with the Mark II detector. This distribution is compared with the second-order QCD prediction and s is determined to be 0.1230.0090.005 at ssSMZ (at the SLAC Linear Collider) and 0.1490.0020.007 at ss=29 GeV (at the SLAC storage ring PEP). The running of s between these two center-of-mass energies is consistent with the QCD prediction. © 1990 The American Physical Society.