[Prex] PREX refuted?

[Jay Benesch]

https://arxiv.org/abs/2603.07597

Constraining the neutron skin of Pb with anisotropic flow in Pb+Pb 
collisions at the LHC

Xin-Li Zhao, Xin-Yi Xie, Yuan Li, Guo-Liang Ma

We study neutron-skin effects of 208Pb in Pb+Pb collisions at 
5.02~TeV using the improved string-melting version of a 
multi-phase transport model by varying the neutron density distribution. 
A systematic response is observed in both the initial eccentricities and 
the anisotropic flow, indicating that neutron-skin effects survive the 
full transport evolution of heavy-ion collisions. A  comparison with 
ALICE data favors small to moderate neutron skin, while large neutron 
skin is excluded. The similar descriptions provided by zero and moderate 
neutron skin point to a geometric degeneracy in the current anisotropic 
flow in Pb+Pb collisions, where anisotropic flow is primarily driven by 
the overall collision geometry and size, thus lacking extreme 
sensitivity to the fine details of the nuclear surface profile. This 
highlights both sensitivity and limitation of constraining neutron-skin 
properties with flow measurements in Pb+Pb collisions at the LHC.
Comments:	8 pages, 8figures
Subjects:	Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)

Tension with CREX relieved.