Absorption of slow negative pions by nuclei

A theory of the inclusive absorption of slow negative pions by nuclei is developed. The theory relies on the local two-nucleon mechanism and on the multiparticle shell model of the nucleus and takes into account pair correlations of the deuteron type at small distances. Formulas for the nuclear widths of the 1S, 2P, 3D, and 4F levels of mesic atoms and for the yields and energy distributions of neutrons and protons are obtained. The yields and energy distributions of correlated nil and np pairs associated with the first, ''hot,'' stage of negative-pion absorption from orbits of mesic atoms are also found. All quantities subjected to investigation are expressed in terms of four constants that determine the nuclear-medium renormalization of the reduced probabilities of the S and P absorption of negative pions by a nucleon pair with zero relative orbital angular momentum and the isospin values of T=0 and 1 in relation to the analogous probabilities for a free nucleon pair.