Dependence of nuclear Z factor on the chemical potential

A simple microscopic formula is derived for the renormalization factor Z of Green's function on the basis of the self-consistency relation of many-bod y theory and the Brueckner method. This formula involves the derivative of the Brueckner G matrix with respect to energy. Based on the analysis of the properties of the G matrix for a slab of nuclear matter, the G matrix is a pproximately replaced by the off-mass-shell T matrix taken for free NN scat tering at a negative energy E equal to the doubled chemical potential mu of the nucleus under consideration. The Z factor thus calculated depends stro ngly on mu and decreases with \mu\. This effect is important for analyzing the properties of atomic nuclei near the drip line, where mu is zero.