Determine the neutron skin type by relativistic isobaric collisions

Abstract

The effects of neutron skin on the multiplicity ($N_{\mathrm{ch}}$) and eccentricity($\hat{I}{\mu }_2$) in relativistic ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV are investigated with the Trento model. It is found that the Ru+Ru/Zr+Zr ratios of the $N_{\mathrm{ch}}$ distributions and $\hat{I}{\mu }_2$ in mid-central collisions are exquisitely sensitive to the neutron skin type (skin vs.~halo). The state-of-the-art calculations by energy density functional theory (DFT) favor the halo-type neutron skin and can soon be confronted by experimental data. It is demonstrated that the halo-type density can serve as a good surrogate for the DFT density, and thus can be efficiently employed to probe nuclear deformities by using elliptic flow data in central collisions. We provide hereby a proof-of-principle venue to simultaneously determine the neutron skin type, thickness, and nuclear deformity.

6 pages, 3 figures. Version published in PLB. Typo in Eq.3 is corrected