Nuclear Geometry-Driven Femtoscopic Correlations in Light-Ion Collisions

Recent anisotropic flow measurements in ${}^{16}\mathrm{O}{+}^{16}\mathrm{O}$ and ${}^{20}\mathrm{N}\mathrm{e}{+}^{20}\mathrm{N}\mathrm{e}$ collisions at a center-of-mass energy per nucleon pair of 5.36~TeV provide evidence for nuclear geometry-driven collectivity. In this Letter, we investigate the femtoscopic signatures of nuclear geometry in these light-ion collision systems, using a hybrid simulation framework that couples $\mathit{\text{ab}}\mathit{\text{initio}}$ nuclear configurations to viscous hydrodynamics and hadronic transport. We show that the $\mathrm{N}\mathrm{e}+\mathrm{N}\mathrm{e}\mathrm{/}\mathrm{O}+\mathrm{O}$ ratio of the freeze-out eccentricity, extracted from azimuthally sensitive femtoscopy, reaches 1.5-1.8 in central collisions for deformed nuclear configurations, compared with about unity for a spherical baseline. This enhancement is significantly larger than that of elliptic flow in the same simulations, and remains stable when pre-equilibrium free streaming is omitted, even though the absolute source radii change considerably. Confronting these predictions with future data will provide new, complementary constraints on nuclear structure and initial-condition modeling.