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Measurements of Light Nuclei (d, t, $^3$He)-$Λ$ Correlations in Au+Au Collisions at $\sqrt{s_{NN}}=3$ GeV from STAR

Xialei Jiang

TL;DR

We measure d–Λ, t–Λ, and $^3$He–Λ momentum correlations in Au+Au collisions at $\sqrt{s_{NN}}=3$ GeV with STAR to probe hyperon–nucleon interactions and the space-time extent of the emission source. The analysis uses femtoscopy and the Lednicky–Lyuboshitz model, parameterized by the scattering length $f_0$ and effective range $d_0$, to extract final-state interaction information from high-statistics data ($\sim2\times10^{9}$ events). The d–Λ correlation shows a strong enhancement at low $k^*$, enabling an estimate of the $^{3}_{\Λ}$H binding energy around $0.06_{-0.02}^{+0.06}$ MeV/$c^2$ with a radius of $16_{-5}^{+5}$ fm, with the doublet $f_0$ favored to be positive but constrained to $[-50,0]$ fm under a bound-state hypothesis. First measurements of t–Λ and $^3$He–Λ correlations are reported, with contamination from hypernuclear decays carefully addressed; future work will extract scattering parameters to constrain binding energies of $^4_{\Λ}$H and $^4_{\Λ}$He, informing hypernuclear structure and neutron-star matter.

Abstract

Heavy-ion collisions offer a unique way to study hyperon-nucleon ($Y$-$N$) interactions through two-particle momentum correlations, which reveal the source's space-time structure and the effects of the final state interactions. Correlations between light nuclei (d, t, $^{3}$He) and $Λ$ provide insight into hypernuclei structure, binding energies, and many-body interactions that might be relevant to the inner structure of neutron stars. This work presents the first measurements of d-$Λ$, t-$Λ$, and $^{3}$He-$Λ$ correlations from $\sqrt{s_{_{\rm NN}}} = 3$ GeV Au+Au collisions collected in 2021 at STAR. Using the Lednicky-Lyuboshitz model, we extract source sizes and interaction parameters, shedding light on hyperon interactions and light hypernuclei structure.

Measurements of Light Nuclei (d, t, $^3$He)-$Λ$ Correlations in Au+Au Collisions at $\sqrt{s_{NN}}=3$ GeV from STAR

TL;DR

We measure d–Λ, t–Λ, and He–Λ momentum correlations in Au+Au collisions at GeV with STAR to probe hyperon–nucleon interactions and the space-time extent of the emission source. The analysis uses femtoscopy and the Lednicky–Lyuboshitz model, parameterized by the scattering length and effective range , to extract final-state interaction information from high-statistics data ( events). The d–Λ correlation shows a strong enhancement at low , enabling an estimate of the H binding energy around MeV/ with a radius of fm, with the doublet favored to be positive but constrained to fm under a bound-state hypothesis. First measurements of t–Λ and He–Λ correlations are reported, with contamination from hypernuclear decays carefully addressed; future work will extract scattering parameters to constrain binding energies of H and He, informing hypernuclear structure and neutron-star matter.

Abstract

Heavy-ion collisions offer a unique way to study hyperon-nucleon (-) interactions through two-particle momentum correlations, which reveal the source's space-time structure and the effects of the final state interactions. Correlations between light nuclei (d, t, He) and provide insight into hypernuclei structure, binding energies, and many-body interactions that might be relevant to the inner structure of neutron stars. This work presents the first measurements of d-, t-, and He- correlations from GeV Au+Au collisions collected in 2021 at STAR. Using the Lednicky-Lyuboshitz model, we extract source sizes and interaction parameters, shedding light on hyperon interactions and light hypernuclei structure.

Paper Structure

This paper contains 6 sections, 2 equations, 4 figures.

Table of Contents

  1. Introduction
  2. Correlation Function and Discussion
  3. d--$\Lambda$ Correlation
  4. t--$\Lambda$ and $^{3}$He--$\Lambda$ Correlation
  5. Summary and Outlook
  6. Acknowledgement

Figures (4)

  • Figure 1: Measured d-$\Lambda$ correlation functions in 0-10% (left), 10-20% (middle) and 20-60% (right) centrality. The black vertical bars and boxes represent the statistical and systematic uncertainties, respectively.
  • Figure 2: Contours of the probability distributions for the extracted final-state interaction (FSI) parameters — scattering length ($f_{0}$) and effective range ($d_{0}$) - for the d-$\Lambda$ system are shown for both the doublet (D, blue) and quartet (Q, orange) spin states. The purple triangles represent predictions from various theoretical models.
  • Figure 3: $\Lambda$ separation energy of $^{3}_{\Lambda}$H ($B_{\Lambda}$). The upper panel displays the probability distribution of the $\Lambda$ separation energy $B_{\Lambda}$. The red point in the lower panel indicates the value of $B_{\Lambda}$ measured in this analysis, with a 95% confidence level. Previous global measurements are also shown for comparison, and their weighted average, $0.19 \pm 0.06$ MeV, is represented by the blue band.
  • Figure 4: Measured t-$\Lambda$ (left) and $^3$He-$\Lambda$ (right) correlation functions for 0–60% centrality. Black vertical bars indicate statistical uncertainties. Systematic uncertainties are not included in the figure.