Correlations between charge radii differences of mirror nuclei and stellar observables

Abstract

The correlation between the charge radii differences in mirror nuclei pairs and the neutron skin thickness has been studied with the so-called finite range simple effective interaction over a wide mass region. The so far precisely measured charge radii difference data within their experimental uncertainty ranges in the ³⁴Ar-³⁴S, ³⁶Ca-³⁶S, ³⁸Ca-³⁸Ar, and ⁵⁴Ni-⁵⁴Fe mirror pairs are used to ascertain an upper limit for the slope parameter of the nuclear symmetry energy <em>L</em> ≈ 100 MeV. This limiting value of L is found to be consistent with the upper bound of the NICER PSR J0740+6620 constraint at 1σ level for the radius R_1.4 of 1.4M neutron stars. The lower bound of the NICER R_1.4 data constrains the lower limit of <em>L</em> to ≈70 MeV. Within the range for <em>L</em> = 70–100 MeV the tidal deformability <em>Lambda</em>^1.4 constraint, which is extracted from the GW170817 event at 2σ level, and the recent PREX-2 and CREX data on the neutron skin thickness are discussed.