On the Enhanced Polarization Due to Channel — Channel Correlations

As it was shown in ref.1–4), the polarization of the inelastically scattered protons on an IAR contains an appreciable contribution from the channel — channel correlations (CCC) betweenthe fluctuating parts of the S-matrix elements. While a complete account of the corelations induced by the doorway — state mechanism is still missing, several approximate expressions for calculating have been proposed. The theory of Abramson et al. 5), labeled hereafter with A, is based on the assumption of the fine structure coupling to the continuum only through the IAR. In theory B of Kawai, Kerman and Mc Voy6) a simple expression is derived in the limit of many directly coupled open channels. A more complete treatment is given by the theory Cl of Engelbrecht and Weidenmuller7). In the limit of many directly coupled channels this theory reduces to the expression B, with an additional term due to the neglect of the mutual level repulsion8). This case will be referred as C2. All these theories have been deduced in the limit of small absorption coefficients. Up to now only the theories A and B were used in fitting the experimental data. No absorption was considered in the resonant channels. Within this assumption, the observables are enhanced independently of the indices c, c′, c″ which gives a complete correlation of the fluctuations of the S-matrix elements between the resonant channels in both theories A and B 3,8).