Small-angle Bhabha scattering data recorded at the Z resonance and large-an
gle Bhabha scattering data recorded at root s = 189 GeV by the L3 detector
at LEP are used to measure the running of the effective fine-structure cons
tant for spacelike momentum transfers. The results are
alpha(-1)(- 2.1 GeV2) -alpha(-1)(-6.25 GeV2) = 0.78 +/- 0.26
alpha(-1)(- 12.25 GeV2) -alpha-(1)(- 3434 GeV2) = 3.80 +/- 1.29,
in agreement with theoretical predictions. (C) 2000 Published by Elsevier S
cience B.V. All rights reserved.