Final state interactions for Bose-Einstein correlations in S+Pb $\to$ $π^+$$π^+$ +X reaction at energy 200GeV/nucleon

Abstract

We applied an analytical formula for Bose-Einstein correlations (BEC) developed by us recently to high-energy heavy ion collisions, in particular to data on S+Pb$\toπ^+$-$π^+$+X reaction at energy $200$ GeV/nucleon reported by the NA44 Collaboration. It takes into account both Coulomb and strong ($π$-$π$~s-wave; I=2) final state interactions (FSI). We have found that inclusion of the strong interaction in addition to Coulomb correction affects significantly the extracted parameters of the BEC like the source size $R$, the degree of coherence $λ$ and the long-range correlation parameter $γ$. In particular, the $λ$ parameter of the BEC is increased by about 20\%. Our results differ from those obtained in $e^+e^-$ annihilation in the following way: the $λ$ parameter does not reach `chaotic limit' and the $γ$ parameter does not approach to zero.