The comparison of characteristics of π? mesons produced in central Mg-Mg interactions with the quark gluon string model predictions

A detailed study of pion production in central Mg-Mg collisions at a momentum of 4.3 GeV/c per incident nucleon was carried out with use of the setup GIBS. The average kinematical characteristics of pions (multiplicity n ₋, momentum P, transverse momentum P _T, emission angle Θ, rapidity Y) and corresponding distributions have been obtained. The experimental results have been compared with the predictions of the Quark Gluon String Model (QGSM) and satisfactory agreement between the experimental data and the model has been found. The QGSM reproduces also the dependence of average P _T on n ₋. The temperatures of π⁻ mesons have been estimated in the rapidity interval of 0.5 ≤ Y ≤ 2.1. A satisfactory fit for π⁻ mesons has been achieved by using a form involving two temperatures T ₁ and T ₂. It is found that the QGSM underestimates T ₂ by (10−15)%. The data have been analyzed using the transverse momentum technique. The observed dependence of the <P _x ^′(Y)> on Y shows the S-shape behaviour. The slope at midrapidity F has been determined. The QGSM reproduces the <P _x> distribution satisfactorily, but underestimates the parameter F. Received: 2 August 1997 / Revised version: 17 November 1997