Multipion dynamics following antiproton annihilation on nuclei

Abstract

Extensive calculations based on our improved version of the intranuclear cascade model for antiproton annihilation in flight on atomic nuclei are presented and compared with experimental data in the LEAR regime. The relationship between the main features of the inclusive proton and pion cross sections and some specific aspects of the cascade dynamics is studied. The sensitivity of the results upon variation of the input data is investigated. In particular it is shown that limited knowledge of medium corrections on pion interactions and of nuclear-structure detail entails such an uncertainty on the predicted high-energy proton cross section that no firm conclusion on the possible signature for unusual phenomena can be drawn from the comparison with experiment. The charged pion multiplicity is particularly studied. The experimental data are reviewed and their inconsistency is underlined. The pion absorption mechanism is discussed in much detail and its influence on the pion yield is exhibited. Medium corrections are discussed. The role of the Δ-degrees of freedom is reanalyzed, and a way to test their relevance is proposed. Existing cascade models are compared with each other and the dispersion of the results is underlined.