DETERMINATION OF EVENT SHAPE DISTRIBUTION AND ALPHA(B)(S) FROM Z(0)-]B(B)OVER-BAR EVENTS AT LEP

In hadronic Z(0) decays collected by the OPAL experiment at LEP, event shape variables such as jet rates, jet masses, thrust and the energy-energy correlation for Z(0) --> b (b) over bar events are compared to those for all flavours using secondary vertex information to tag the b quarks. The measured distributions are found to be well described by an O(alpha(s)) calculation for heavy quarks as well as by parton shower simulations. We also determine the ratio of the strong coupling constant for b quacks and all quarks, alpha(s)(b)/alpha(s)(incl), from these distributions. We find alpha(s)(b)/alpha(s)(incl) = 0.994 +/- 0.005 (+0.010)(-0.012), where the errors are the statistical and systematic errors. The result can be converted into the ratio for b quarks relative to the complementary flavours udsc alpha(s)(b)/alpha(s)(udsc) = 0.992 +/- 0.007 (+0.013)(-0.015).