Event shapes for hadronic final state: experimental review

Abstract

Analysis is presented for first moments of collective observable distributions in two-jet events for various interaction types and for wide initial energy range. These variables include sphericity, thrust, components of transverse particle momentum, alignment and planarity. Analytical functions are suggested for description of energy dependence for all collective variables under study with exception of infrared-stable thrust variable. Energy dependence for average thrust is compared with predictions of dispersive model and single dressed gluon approximation. Estimations of strong coupling constant obtained in the paper are in reasonable agreement both with world average value and with results extracted by other methods. Usually, multiplicity dependence of collective variables under study agree with power function at energies less than 12 GeV at qualitative level.