Charge density of light exotic nuclei and ρNN tensor coupling

We use a relativistic mean field model to study the charge density distributions of exotic oxygen isotopes. Nonlinear isoscalar-isovector terms which are not constrained by the present data are considered and the ρNN tensor coupling that does not affect the symmetry energy in the mean field model is included. Strong correlations between the neutron radius of Pb and the charge radius of O are found. The ρNN tensor coupling explicitly enhances the radius correlations between O and Pb. This enhancement is due to the neutron occupation of the orbital 2s1/2. The charge radius is sensitive to the change of the density dependence of the symmetry energy as the isotope goes towards the proton drip line. PACS: 21.10.Ft, 21.60.-n, 27.30.+t, 27.20.+n