Disentangling baryon stopping and neutron skin effects in heavy-ion collisions

Abstract

We analyse the net baryon (B) and net electric charge (Q) stopping in heavy-ion collisions using the statistical model. Focusing first on isobar collisions $\mathrm{R}u+\mathrm{R}u$ and $\mathrm{Z}r+\mathrm{Z}r$ at $\sqrt{s_{\mathrm{N}N}}=200$ GeV, we show that any deviation of the midrapidity ratio NB/NQ from the valence-correlated charge-to-baryon ratio baseline, A/Z—often referred to as excess baryon stopping—can be quantitatively extracted from RHIC measurements of charge- and baryon-stopping ratios. We then generalize the approach to other collision systems at RHIC and LHC energies and introduce an oxygen-baseline observable, r^OY, whose central-to-peripheral ratio, ${\mathcal{R}}^{OY}$, exhibits strong and systematic sensitivity to the neutron-skin thickness of the target nucleus Y.