Probing the octupole deformation of ${}^{238}$U in high-energy nuclear collisions

Some atomic nuclei exhibit ``pear" shapes arising from octupole deformation (${\beta }_3$), though direct experimental evidences for such exotic shapes remains scarce. Low-energy model studies suggest ${}^{238}$U may have a modest octupole deformation arising from collective vibrational degrees of freedom, in addition to a large prolate shape. We investigated the impact of this modest octupole shape on observables involving triangular flow ($v_3$) in high-energy nuclear collisions. Using a hydrodynamic framework, we show $v_3$ and its correlation with mean transverse momentum, $⟨v_3^2\delta p_{\mathrm{T}}⟩$, exhibit strong sensitivity to ${\beta }_3$. We found that $⟨v_3^2⟩$ follows a linear increase with ${\beta }_3^2$, while the characteristic anticorrelation in $⟨v_3^2\delta p_{\mathrm{T}}⟩$ shows a pronounced ${\beta }_3$-dependent suppression. Our findings demonstrate that the collective-flow-assisted nuclear imaging method in high-energy nuclear collisions, when compared with experimental data, can provide unique quantitative constraints on higher-order deformations.