Energy dependence of inclusive pion spectra in pion-induced reactions and the thermodynamic model

Abstract

The inclusive single-particle spectra according to the thermodynamic model were extensively calculated and compared to experixnental data from pp collisions (1-3) and m o ~ recently for Kp collisions (4). A remarkable agreement with the experimental data was found generally with inclusive spectra of pions, kaons, protons and antinueleons. The thermodynamic description of single-particle spectra was improved recently (3) by using the strong thermodynamic bootstrap solution (5-7). We describe here the calculation of inclusive pion spectra in =• collisions using essentially the strong thermodynamic bootstrap method which was described by HAGEDORN and RANFT (3) for pp collisions. This method has to be modified because of the nonsymmetrical particles in the initial state along the lines descussed by MATTHXU8 and RA~FT (a). A second modification of the method consists in the introduction of a rapidi ty weight function of fireballs G(~) instead of the velocity weight function F(~) used in ref. (1) to (4). The eascadelike decay chain of fireballs is one of the new features of the strongbootstrap thermodynamic model (3) agMnst the weak-bootstrap description (1.2). A fireball decay chain muliplicity function q(,L r0) was introduced to describe the change in mult ipl ici ty caused by the decay chain. This function differs slightly for pion-induced fireballs and proton-induced fireballs, a difference which we find essential for the understanding of the inclusive pion spectra in the =p collisions at present accelerator energies. The description of the pion spectra with the weak thermodynamic bootstrap model (3) was not possible without the introduction of one new parameter which does not appear in the description presented here. The most essential contribution to the inclusive thermodynamic pion spectra concerns the free production of pions without restrictions from conservation laws. Using