English

Triaxial shapes and the angular structure of nuclear three-body correlations

Nuclear Theory 2026-04-02 v1 High Energy Physics - Experiment High Energy Physics - Phenomenology Nuclear Experiment

Abstract

Relativistic nuclear collisions have emerged as a new tool for probing many-body correlations of nucleons in the ground states of atomic nuclei. Here, we investigate the connection between three-nucleon correlations inside nuclei and three-particle correlations measured in collider final states. We work within a classical rigid-rotor picture of the colliding ions, whereby correlations in the lab frame arise solely from the averaging over orientations of an intrinsic-frame nucleon density with a triaxial quadrupole deformation, characterized by Bohr parameters β2\beta_2 and γ\gamma. With a Gaussian Ansatz for the density, we derive the leading-order form of the resulting two- and three-body nucleon distributions and perform a detailed analysis of their harmonic structure. With this, we provide an analytical understanding of empirical results linking shape parameters to final-state observables, notably, the fact that the covariance of the squared elliptic flow (v22v_2^2) with the mean transverse momentum ([pT][p_T]), as well as the skewness of [pT][p_T] fluctuations, are to leading order proportional to β23cos(3γ)\beta_2^3 \cos(3\gamma). This elucidates the connection between three-nucleon densities, nuclear triaxiality, and three-particle correlations in high-energy nuclear collisions.

Keywords

Cite

@article{arxiv.2604.00619,
  title  = {Triaxial shapes and the angular structure of nuclear three-body correlations},
  author = {Hadi Mehrabpour and Giuliano Giacalone and Matthew W. Luzum},
  journal= {arXiv preprint arXiv:2604.00619},
  year   = {2026}
}

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11 pages