Multiplicity with a thrust cut

We evaluate the multiplicity of hadrons in thee ⁺ e ^–-annihilation at a given thrustT in the modified leading-log approximation, including corrections. The calculation is done at a large value of =1–T by the use of the factorisation which takes place in the one-particle-inclusive cross section at a given . At a small , a different type of factorisation takes place, which also enable us to evaluate the multiplicity. Two approaches are compared numerically. Measuring this quantity near =1/3, we can determine the multiplicity ratio between a gluon-jet and a quark-jet.