The jet multiplicity as a function of thrust

We calculate the average multiplicity of jets in e+e- annihilation as a function of both the jet resolution parameter, ycut, and the thrust T. Our result resumes to all orders the leading and next-to-leading logarithms in ycut and 1 - T, and is exact up to second order in as. This allows a comparison between the number of jets found using jet algorithms and the ability to distinguish different jet topologies via thrust. (author)