Surface tension in a compressible liquid-drop model: Effects on nuclear density and neutron skin thickness

We examine whether or not the surface tension acts to increase the nucleon density in the nuclear interior within a compressible liquid-drop model. We find that it depends on the density dependence of the surface tension, which may in turn be deduced from the neutron skin thickness of stable nuclei.

Figure 1

Difference in the root-mean-square radius between neutrons and protons for six stable nuclei of $A>50$. The squares and crosses denote the results calculated from Eq. (23) for $\chi =0$ and $4∕3$; the other parameters are set to be $n_0=0.16{\text{fm}}^{-3}$, $S_0=30\text{MeV}$, $K_0=230\text{MeV}$, $L=100\text{MeV}$, ${\sigma }_0=1\text{MeV}{\text{fm}}^{-2}$, $C_{\text{sym}}=1.8$, and $R_p=1.2A^{1∕3}\text{fm}$. The empirical data (dots) are taken from Refs. 13, 14.