Rapidity and Angular Distributions of Charged Secondaries According to the Hydrodynamical Model of Particle Production

Abstract

Recent measurements of inclusive production cross sections are analyzed in the framework of the Landau hydrodynamical model of particle production. We also give a critical analysis of recent data and the variables used in their presentation. It is concluded that the evidence for a flat rapidity distribution in the central region is not compelling. Except possibly at the very highest available ISR (CERN Intersecting Storage Rings) energy, the Landau Gaussian gives an excellent description of the rapidity distribution of the nonleading charged secondaries. The calculation of distributions in the variable $\eta =-\ln tan\left(\frac{\theta }{2}\right)$ from given rapidity and transverse momentum distributions is worked out in many interesting cases. The Landau rapidity distribution is cast in a universal (energy dependent) scaling law which agrees well with available data. The angle and energy dependence of charged secondaries near 90° in the c.m. system in $\mathrm{pp}$ collisions agrees well with the theoretical prediction. Finally it is shown that the hydrodynamical model leads to approximate Feynman scaling except for very small values of $x=\frac{2p}{\sqrt{s}}$, where large deviations from scaling are predicted.