2026/07/21 by Myeong-Hwan Mun, Kyoungsu Heo, Jubin Park +2
Physics and Astronomy · #nucl-th
9 page, 2 figure, 5 tables
arxiv created 2026/07/31 · arxiv updated 2026/08/03
Mirror charge radii can constrain neutron skins only if nuclear isospin-symmetry breaking beyond the Coulomb interaction is controlled. We present a differential Skyrme energy-density-functional analysis in which mirror displacement energies (MDEs) and mirror charge-radius differences are generated by the same class-III charge-symmetry-breaking (CSB) functional. Starting from self-consistent Coulomb-only SLy4 and SkM* baselines, we map Coulomb-subtracted MDE residuals onto volume and surface-gradient CSB terms. The MDEs determine the nearly degenerate volume-surface direction, while the measured anchor radii select the point on that direction used for target predictions, without introducing radius-specific parameters. Measured pairs 34Ar-34S, 36Ca-36S, 38Ca-38Ar, and 54Ni-54Fe form compact surface-gradient-like response classes, with λB=1.32±0.04~fm-2 for SLy4 and 1.20±0.05~fm-2 for SkM*. MDEs therefore constrain mainly the effective combination t0III-λclCΔIII, rather than the two couplings separately. A joint volume-plus-surface-gradient fit gives MDE and ΔR\rm ch\rm mirr RMS residuals of 0.0529 MeV and 0.0031 fm in SLy4; SkM* recovers the response class but gives a larger ΔR\rm ch\rm mirr residual. Calibrated response changes proton-rich mirror skins at the 10-2 fm level and yields charge radius predictions for 40Ti, 42Ti, 46Cr, and 50Fe, with an SLy4 - SkM* spread of up to 0.021 fm. Surface-gradient-sensitive CSB corrections must therefore be quantified before mirror charge-radius differences are used as clean neutron-skin or symmetry-energy probes. The agreement of SLy4 and SkM* in the response-class assignment is more robust than their absolute radius corrections, which remain EDF dependent.