Speaker
Description
Collectivity in small collision systems at both RHIC and the LHC have attracted considerable attention regarding the origin of azimuthal anisotropy and the light nuclei structure. Recent measurements have established a geometry-driven picture through the comparison of $v_2\{2\}$ and $v_2\{4\}$ in $d$+Au and $^{16}$O+$^{16}$O collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV at STAR, underscoring the important role of the initial-state geometry [1]. As this geometry is directly shaped by the underlying nuclear structure, ab-initio models have investigated several observables and suggest that the $v_n$–$[p_\mathrm{T}]$ correlations and $[p_\mathrm{T}]$ fluctuations are particularly sensitive to the intrinsic structure of $^{16}$O, in particular, its possible $\alpha$-clustering configurations [2,3].
With data from STAR, we present systematic measurements of the $v_n$–$[p_\mathrm{T}]$ correlations and $[p_\mathrm{T}]$ fluctuations in both $d$+Au and $^{16}$O+$^{16}$O collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV. The results are compared with theoretical predictions incorporating different ab-initio nuclear structure inputs, including configurations with and without $\alpha$ clustering. These comparisons offer new insight into the cluster patterns of light nuclei across energy scales and shed light on initial conditions of quark-gluon plasma and collective dynamics in small relativistic collision systems.
[1] STAR Collaboration, ``Engineering the shapes of quark-gluon plasma droplets by comparing anisotropic flow in small symmetric and asymmetric collision systems", arXiv: 2510.19645
[2] C. Zhang, J. Chen, G. Giacalone, S. Huang, J. Jia, Y.-G. Ma, Physics Letters B 862, 139322 (2025)
[3] S. Huang, J. Jia, C. Zhang, Physics Letters B, 870, 139926 (2025)
