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

Measurements of Rb, the ratio of the bb¯ cross-section to the qq¯ 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.