Poisson-Like Shape and Shoulder Structure of Hadron Multiplicity Distributions in e⁺e^- Annihilation at Z⁰ Energy

Abstract：

The charged multiplicity distributions of final state hadrons in the e⁺e^- annihilation at 91.2 GkV Z⁰ energy region are fitted with Poisson shape in different rapidity windows for full-jets and double jets events in double and single hemisphere. The multiplicity distributions which are in Poisson-like shape are obtained according to the parameter <n>/D and the fitting quality, and are compared with the results derived from the relevant theoretical models. The relationship between Poisson-like shape and KNO scaling is discussed. The connection between the parameters expressing the deviation from the Poisson shape and non-independent particle emission, as well as multiplicity correlation strength is analyzed. The "shoulder structure" is observed in single hemisphere for central rapidity region and analyzed by using the JADE jet analysis algorithm.