Measurements of Rb in e+e-collisions at √s between 182 and 209 GeV

Measurements of R-b, the ratio of the b (b) over bar cross-section to the q (q) over bar cross-section in e(+)e(-) collisions, are presented. The data were collected by the OPAL experiment at LEP at centre-of-mass energies between 182 and 209 GeV Lepton, lifetime and event-shape information is used to tag events containing b quarks with high efficiency. The data are compatible with the Standard Model expectation. The mean ratio of the eight measurements reported here to the Standard Model prediction is 1.055 +/- 0.031 +/- 0.037, where the first error is statistical and the second systematic. (c) 2005 Elsevier B.V. All rights reserved.