HADRONIC INTERACTIONS AT THE CERN SPS: RESONANCE DECAYS VERSUS PARTON DYNAMICS

Abstract

Using new data on pion production in p + p interactions from the NA49 experiment, it is demonstrated that the detailed features of double differential pion cross sections are well reproduced over most of the phase space from the decay of a representative sample of known mesonic and baryonic resonances. Thirteen resonances reaching up to spin four tensor-mesons and including the newly measured N * states up to the N *(1680) have been used. The pT integrated Feynman xF distributions in the high-xF region 0.4 < xF < 0.9 are quantitatively reproduced as well as the pT distributions up to 2 GeV/c and beyond at all xF. In both these phase space regions direct effects of parton dynamics such as valence quark fragmentation or parton scattering are generally evoked in order to provide a basis of understanding. The saturation of the measured yields by resonance decay casts a doubt on these assumptions.