Neutron skin and centrality classification in high-energy heavy-ion collisions at the LHC

The concept of centrality in high-energy nuclear collisions has recently become a subject of an active debate. In particular, the experimental methods to determine the centrality that have given reasonable results for many observables in high-energy lead–lead collisions at the LHC have led to surprising behavior in the case of proton–lead collisions. In this letter, we discuss the possibility to calibrate the experimental determination of centrality by asymmetries caused by mutually different spatial distributions of protons and neutrons inside the nuclei — a well-known phenomenon in nuclear physics known as the neutron-skin effect.