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| Format: | Preprint |
| Published: |
2025
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| Online Access: | https://arxiv.org/abs/2512.05614 |
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| _version_ | 1866918233800441856 |
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| author | Zhang, Chunjian |
| author_facet | Zhang, Chunjian |
| contents | We present a novel ``imaging-by-smashing" approach for probing nuclear deformation in high-energy heavy-ion collisions. By analyzing anisotropic-flow ($v_n$) and mean transverse momentum ($\left[p_T\right]$)-based observables in collisions of highly deformed $^{238} \mathrm{U}$ nucleus and nearly spherical $^{197} \mathrm{Au}$ nucleus, we extract the deformation parameters of $^{238}$U. The key observables include the variances $\left\langle v_n^2\right\rangle,\left\langle\left(δp_T\right)^2\right\rangle$, and the covariance $\left\langle v_n^2 δp_T\right\rangle$. Ratios of these observables between $^{238}$U+$^{238}$U and $^{197}$Au+$^{197}$Au collisions largely cancel final-state effects, thereby isolating the influence of nuclear deformation. We further report the first experimental indication of octupole deformation in $^{238}$U via $v_3$-based observables~\cite{2025rot}. The extracted deformation parameters, comparing with state-of-the-art hydrodynamic model calculations, are consistent with low-energy nuclear structure data. These results establish high-energy collisions as a powerful probe of nuclear shapes on femtosecond timescales. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_05614 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Evidence for modest octupole deformation in $^{238}$U from high-energy heavy-ion collisions Zhang, Chunjian Nuclear Experiment High Energy Physics - Experiment We present a novel ``imaging-by-smashing" approach for probing nuclear deformation in high-energy heavy-ion collisions. By analyzing anisotropic-flow ($v_n$) and mean transverse momentum ($\left[p_T\right]$)-based observables in collisions of highly deformed $^{238} \mathrm{U}$ nucleus and nearly spherical $^{197} \mathrm{Au}$ nucleus, we extract the deformation parameters of $^{238}$U. The key observables include the variances $\left\langle v_n^2\right\rangle,\left\langle\left(δp_T\right)^2\right\rangle$, and the covariance $\left\langle v_n^2 δp_T\right\rangle$. Ratios of these observables between $^{238}$U+$^{238}$U and $^{197}$Au+$^{197}$Au collisions largely cancel final-state effects, thereby isolating the influence of nuclear deformation. We further report the first experimental indication of octupole deformation in $^{238}$U via $v_3$-based observables~\cite{2025rot}. The extracted deformation parameters, comparing with state-of-the-art hydrodynamic model calculations, are consistent with low-energy nuclear structure data. These results establish high-energy collisions as a powerful probe of nuclear shapes on femtosecond timescales. |
| title | Evidence for modest octupole deformation in $^{238}$U from high-energy heavy-ion collisions |
| topic | Nuclear Experiment High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2512.05614 |