[Prex] Ab initio predictions link the neutron skin of 208Pb to nuclear forces

[Jay Benesch]

just in case you didn't check this morning

https://arxiv.org/abs/2112.01125

Ab initio predictions link the neutron skin of 208Pb to nuclear forces
Baishan Hu, Weiguang Jiang, Takayuki Miyagi, Zhonghao Sun, Andreas 
Ekström, Christian Forssén, Gaute Hagen, Jason D. Holt, Thomas 
Papenbrock, S. Ragnar Stroberg, Ian Vernon

     Heavy atomic nuclei have an excess of neutrons over protons. This 
leads to the formation of a neutron skin whose thickness, Rskin, is 
sensitive to details of the nuclear force -- linking atomic nuclei to 
properties of neutron stars, thereby relating objects that differ in 
size by 18 orders of magnitude [1, 2]. 208Pb is of particular interest 
here because it exhibits a simple structure and is accessible to 
experiment. However, computing such a heavy nucleus has been out of 
reach for ab initio theory. By combining advances in quantum many-body 
methods, statistical tools, and emulator technology, we make 
quantitative predictions for the properties of 208Pb starting from 
nuclear forces that are consistent with symmetries of low-energy quantum 
chromodynamics. We explore 109 different nuclear-force parameterisations 
via history matching, confront them with data in select light nuclei, 
and arrive at an importance-weighted ensemble of interactions. We 
accurately reproduce bulk properties of 208Pb and find 
Rskin(208Pb)=0.14−0.20 fm which is smaller than a recent extraction from 
parity-violating electron scattering [3] but in agreement with other 
experimental probes. The allowable range of Rskin(208Pb) is 
significantly constrained by nucleon-nucleon scattering data, ruling out 
very thick skins. This work demonstrates that nuclear forces constrained 
to light systems extrapolate reliably to even the heaviest nuclei, and 
that we can make quantitative predictions across the nuclear landscape.