Compression-mode resonances in the calcium isotopes and implications for the asymmetry term in nuclear incompressibility

TL;DR

This study investigates the isoscalar giant monopole resonance in calcium isotopes to clarify the sign of the asymmetry term in nuclear incompressibility, with implications for nuclear physics and astrophysics.

Contribution

It provides new experimental data that conclusively refutes the positive value of the asymmetry term, aligning with previous measurements and challenging existing theoretical models.

Findings

Results discount positive $K_\tau$ values.

Data consistent with previous measurements.

Implications for nuclear matter models.

Abstract

Recent data on isoscalar giant monopole resonance (ISGMR) in the calcium isotopes $^{40,44,48}$Ca have suggested that $K_\tau$, the asymmetry term in the nuclear incompressibility, has a positive value. A value of $K_\tau > 0$ is entirely incompatible with present theoretical frameworks and, if correct, would have far-reaching implications on our understanding of myriad nuclear and astrophysical phenomena. This paper presents results of an independent ISGMR measurement with the $^{40,42,44,48}$Ca($\alpha,\alpha^\prime$) reaction at $E_\alpha = 386$ MeV. These results conclusively discount the possibility of a positive value for $K_\tau$, and are consistent with the previously-obtained values for this quantity.