On the excluded space in applications of Feshbach projection formalism

TL;DR

This paper examines the impact of the remainder in truncated excluded spaces within the Feshbach projection formalism, emphasizing the importance of addressing these effects for accurate nuclear structure and reaction models.

Contribution

It highlights the necessity of considering the effects of the remainder in truncated spaces to ensure the physical validity of Feshbach formalism applications.

Findings

Truncated excluded spaces are commonly used in nuclear models.

The effects of the remainder in these truncations are significant.

Addressing the remainder improves the physical reliability of the models.

Abstract

Various model applications in nuclear structure and reactions have been formulated starting with the Feshbach projection formalism. In recent studies a truncated excluded space has been enumerated to facilitate calculation and identify a convergence in expansions within that truncation. However, the effect of any remainder must be addressed before results from such can be considered physical.