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arXiv · 1510.04066

New formulae for the $(-2)$ moment of the photo-absorption cross section, $σ_{_{-2}}$

Nico Orce
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Abstract

Two new formulae for the $(-2)$ moment of the photo-absorption cross section, $σ_{_{-2}}$, have been determined, respectively, from the 1988 compilation of Dietrich and Berman and a mass-dependent symmetry energy coefficient, $a_{sym}(A)$. The data for $A\gtrsim50$ follow, with a {\small $RMS$} deviation of 6\%, the power-law $σ_{_{-2}}=2.4 A^{5/3}$$μ$b/MeV, which is in agreement with Migdal's calculation of $σ_{_{-2}}=2.25A^{5/3}$$μ$b/MeV based on the hydrodynamic model and the $σ_{_{-2}}$ sum rule. The additional inclusion of $a_{sym}(A)$ provides a deeper insight to the nuclear polarization of $A\geqq10$ nuclei.

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Nico Orce. 2015-10-14. New formulae for the $(-2)$ moment of the photo-absorption cross section, $σ_{_{-2}}$. https://doi.org/10.1103/physrevc.91.064602

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