English

Mapping Nuclear Deformation with Differential Radial Flow in Heavy-Ion Collisions

Nuclear Theory 2026-02-05 v1 High Energy Physics - Phenomenology Nuclear Experiment

Abstract

In relativistic heavy-ion collisions, the radial flow of the fireball, usually characterized by transverse momentum spectra of final-state particles, encodes essential information about the hot and dense nuclear matter created in the collisions. However, the response of radial flow, including its pTp_T-differential structure v0(pT)v_0(p_T) and longitudinal fluctuations v0(η)v_0(\eta), to intrinsic nuclear deformation remains unexplored. Using realistic (3+1)(3+1)-dimensional viscous hydrodynamic calculations with Trento-3D initial conditions, we investigate how nuclear deformation affects the differential radial flow. We observe a clear, positive correlation between quadrupole deformation β2\beta_2 and radial flow: both magnitudes of v0v_0 and v0(pT)v_0(p_T) are enhanced in central collisions when β2\beta_2 is increased. In contrast, the Pearson coefficient ρ(n(pT),[pT])\rho(n(p_T), [p_T]) exhibits a universal step-like behavior across all collision systems and centralities. Further analysis of longitudinal decorrelation of radial flow reveals a rich structure: in central collisions, large β2\beta_2 tends to suppress the decorrelation, whereas hexadecapole deformation β4\beta_4 tends to enhance it. Such decorrelation effect increases toward peripheral collisions. Our results demonstrate that precise measurements of radial flow, spanning transverse momentum and longitudinal dependences, can provide powerful, complementary constraints on nuclear deformation in high-energy nucleus-nucleus collisions.

Keywords

Cite

@article{arxiv.2602.04148,
  title  = {Mapping Nuclear Deformation with Differential Radial Flow in Heavy-Ion Collisions},
  author = {Jie Zhu and Xiang-Yu Wu and Guang-You Qin},
  journal= {arXiv preprint arXiv:2602.04148},
  year   = {2026}
}

Comments

12 pages, 11 figures