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Anisotropic Flow of light (anti-)(hyper-)nuclei in Pb+Pb Collision at $\sqrt{s_{NN}}=5.36$ TeV

Fu Ma, Zheng-Qing Wang, Xiong-Hong He, Che Ming Ko, Qi-Ye Shou, Kai-Jia Sun, Wenbin Zhao, Wen-Hao Zhou

Abstract

Using the coalescence model with nucleon phase-space distributions generated by the hybrid MUSIC framework, we study the elliptic flow ($v_2$) and triangular flow ($v_3$) of (anti-)protons, (anti-)deuterons, (anti-)$^3\mathrm{He}$, and ${^3_Λ\mathrm{H}}$ in Pb+Pb collisions at $\sqrt{s_{NN}} = 5.36$ TeV. We find that the simple $v_2$ scaling with the number of constituent nucleons $A$ breaks down at high transverse momentum $p_T/A > 1.5$ GeV/$c$, while an improved scaling relation holds well up to $p_T/A \approx 3$ GeV/$c$. In contrast, $v_3$ exhibits similar behavior under both scaling prescriptions, with no significant difference. We also make predictions for $v_2$ and $v_3$ of the hypertriton and find these flows are insensitive to the Lambda-deuteron ($Λ-d$) distance inside the hypertriton. Our results are compared with preliminary experimental measurements by the ALICE Collaboration and offer insight into the production mechanisms of light (anti-)(hyper-)nuclei in high-energy heavy-ion collisions.

Anisotropic Flow of light (anti-)(hyper-)nuclei in Pb+Pb Collision at $\sqrt{s_{NN}}=5.36$ TeV

Abstract

Using the coalescence model with nucleon phase-space distributions generated by the hybrid MUSIC framework, we study the elliptic flow () and triangular flow () of (anti-)protons, (anti-)deuterons, (anti-), and in Pb+Pb collisions at TeV. We find that the simple scaling with the number of constituent nucleons breaks down at high transverse momentum GeV/, while an improved scaling relation holds well up to GeV/. In contrast, exhibits similar behavior under both scaling prescriptions, with no significant difference. We also make predictions for and of the hypertriton and find these flows are insensitive to the Lambda-deuteron () distance inside the hypertriton. Our results are compared with preliminary experimental measurements by the ALICE Collaboration and offer insight into the production mechanisms of light (anti-)(hyper-)nuclei in high-energy heavy-ion collisions.

Paper Structure

This paper contains 10 sections, 12 equations, 5 figures, 1 table.

Table of Contents

  1. INTRODUCTION
  2. Methods
  3. Results
  4. Transverse momentum spectra of light nuclei
  5. Nucleon number scaling of light nuclei anisotropic flow
  6. Angular distributions
  7. Anisotropic flow of (anti-)hypertriton
  8. Comparison with preliminary experimental data
  9. Summary
  10. Acknowledgments

Figures (5)

  • Figure 1: Invariant transverse momentum ($p_T$) spectra of protons ($p+\bar{p}$), deuterons ($d+\bar{d}$), and helium-3 ($^{3}\mathrm{He}+^{3}\overline{\mathrm{He}}$) at midrapidity ($-0.5 < y < 0.5$) in Pb+Pb collisions at $\sqrt{s_{NN}} = 5.36$ TeV. The theoretical predictions from the hybrid dynamical approach coupled with the nucleon coalescence model are shown for three centrality classes (0--20%, 20--40%, and 40--60%). For clarity within a single panel, the spectra for different centralities are scaled by factors of $2^n$ ($n=2, 1, 0$).
  • Figure 2: Panels (a)-(f) show $v_2(p_T)$ and $v_3(p_T)$ for Pb+Pb collisions at $\sqrt{s_{NN}}=5.36$ TeV in the 0-20%, 20-40% and 40-60% centrality classes for different particles: (anti-)proton (a, d), (anti-)deuteron (b, e ) and (anti-)Helium-3 (c, f). The solid lines are results obtained using Eq.(\ref{['eq:ImprovedScaling']}), while the dashed lines correspond to Eq. (\ref{['eq:SimpleScaling']}).
  • Figure 3: Normalized azimuthal distributions of proton (left), deuteron (middle) and $^3$He (right) relative to $\Psi_2$ (top) and $\Psi_3$ (bottom) in the 40%–60% centrality class. Symbols represent the result from the coalescence model ($v^{Coal}_n$), while the dashed lines show the scaling expectation $\left(\frac{d N_p}{d\phi}\right)^{A}$ ($v^{Scal}_{n}$). The transverse momentum ranges are $1.67\!<\!p_T\!<\!2.0\,$GeV/$c$ (proton), $3.33\!<\!p_T\!<\!4.0\,$GeV/$c$ (deuteron), and $5.00\!<\!p_T\!<\!6.0\,$GeV/$c$ ($^3$He). The extracted flow coefficients are shown in each panel.
  • Figure 4: $v_2(p_T)$ and $v_3(p_T)$ of (anti-)hypertriton for different values of the parameters $\sigma_{\lambda}$ in the $0-20\%$(left), $20-40\%$(middle) and $40-60\%$(right) centrality classes in Pb+Pb collision at $\sqrt{s_{NN}}=5.36$TeV.
  • Figure 5: Panel (a): $v_{2}(p_T)$ of ($^3\overline{\mathrm{He}}$) in Pb–Pb collisions at $\sqrt{s_{NN}}=5.36\,$TeV for the 20–30% centrality class. Panel (b): $v_{2}(p_T)$ of $^3\mathrm{He}$ and $_{\Lambda}^3\mathrm{H}$ in the same system for the 20–60% centrality class. The preliminary ALICE data are taken from Ref. alicecollaboration2026measurementellipticflow3he.