Sensitivity of neutron radii in a208Pb nucleus and a neutron star to nucleon-σ-ρ coupling corrections in relativistic mean field theory
We study the sensitivity of the neutron skin thickness S in a 208Pb nucleus to the addition of nucleon-σ-ρ coupling corrections to a selection (PK1, NL3, S271, and Z271) of interactions in a relativistic mean field model. The PK1 and NL3 effective interactions lead to a minimum value of S = 0.16 fm in comparison with the original value of S = 0.28 fm. The S271 and Z271 effective interactions yield even smaller values of S = 0.11 fm, which are similar to those for nonrelativistic mean field models. A precise measurement of the neutron radius, and therefore S, in 208Pb will place an important constraint on both relativistic and nonrelativistic mean field models. We also study the correlation between the radius of a 1.4-solar-mass neutron star and S. ©2005 The American Physical Society.