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arXiv · 2508.09890

Separable character of ab initio No-Core Shell Model one-body densities

J. Foy·Ch. Elster·P. Maris·S. P. Weppner·S. K. Bogner
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Abstract

Motivated by recent findings on the separability of optical potentials that are derived from folding off-shell densities with off-shell nucleon-nucleon amplitudes, we study the off-shell character of one-body density matrices created within the No-Core Shell Model (NCSM). Concentrating on nuclei with a 0$^+$ ground state from $^4$He through $^{48}$Ca, we investigate the off-shell character of their one-body density matrices in momentum space when using the momentum transfer and the average momentum as variables. A singular value decomposition of the one-body density matrices reveals that they can be characterized by only very few terms, depending on the mass number of the nucleus. These findings are independent of the nucleon-nucleon interactions employed, as well as from computational specifics as grid spacing and size of the model space.

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J. Foy, Ch. Elster, P. Maris, S. P. Weppner, S. K. Bogner. 2026-03-12. Separable character of ab initio No-Core Shell Model one-body densities. https://arxiv.org/abs/2508.09890

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