Exploring the compactness of $α$ cluster in $^{16}$O nuclei with relativistic $^{16}$O+$^{16}$O collisions (2401.15723v4)

Abstract: Probing the $\alpha$ cluster of $^{16}$O with the relativistic $^{16}$O+$^{16}$O collisions has raised great interest in the heavy ion community. However, the effects of the $\alpha$ cluster on the soft hadron observables vary largely among different studies. In this paper, we explain the differences by the compactness of the $\alpha$ cluster in oxygen, using iEBE-VISHNU hydrodynamic simulations with different initial state $\alpha$ cluster configurations. We also find several observables, such as the intensive skewness of the $[p_{\rm T}]$ correlator $\Gamma_{p_{\rm T}}$, the harmonic flows $v_2{2}$, $v_2{4}$, $v_3{2}$, and the $v_n^2-\delta[p_{\rm T}]$ correlations $\rho(v_{2}^{2}, [p_{\rm T}])$, $\rho(v_{3}^{2}, [p_{\rm T}])$ in $^{16}$O+$^{16}$O collisions are sensitive to the compactness of the $\alpha$ cluster in the colliding nuclei, which can be used to constrain the configurations of $^{16}$O in the future. Our study serves as an important step toward the quantitative exploration of the $\alpha$ cluster configuration in the light nuclei with relativistic heavy ion collisions.

• The paper demonstrates that compact α clusters in 16O nuclei induce a non-monotonic dependence of mean transverse momentum on collision centrality.
• The paper reveals that compact cluster configurations significantly modify elliptic and triangular flow harmonics, affecting v2 and v3 ratios.
• The paper shows that Pearson correlation coefficients between flow harmonics and momentum observables serve as sensitive probes of α clustering effects.

Analysis of Alpha Cluster Compactness in Nuclei through Relativistic Collisions

The paper "Exploring the Compactness of α Cluster in $^{16}$O Nuclei with Relativistic $^{16}$O+$^{16}$O Collisions" provides a comprehensive examination of α cluster configurations within oxygen nuclei. Utilizing relativistic heavy ion collision experiments, the authors explore the impact of these configurations on soft hadron observables, aiming to understand the α cluster's compactness within the nuclei and its implications on physical observables.

The paper leverages a sophisticated event-by-event hybrid model that includes the \trento\ model for initial stage generation, \vis{} for describing the collective expansion of the quark-gluon plasma (QGP), and \urqmd\ for simulating the hadron cascade. By simulating $^{16}$O+$^{16}$O collisions at $\sqrt{s_{\rm NN}}=6.5$ TeV, they seek to discern the influence of α clustering on various final state observables.

Observables and Findings

The paper investigates several key observables sensitive to the α cluster configurations:

1. Transverse Momentum ($[p_{\rm T}]$): The paper indicates that the presence of compact α clusters can lead to non-monotonic centrality dependencies in the mean transverse momenta ($\langle p_{\rm T} \rangle$). This is attributed to variations in the density within the overlap region of colliding nuclei, where compact clusters can either reduce or enhance $\langle p_{\rm T} \rangle$ depending on collision centrality.
2. Elliptic and Triangular Flows ($v_n$): Elliptic flow ($v_2$) and triangular flow ($v_3$) observables reveal dependency on α cluster configurations, with notable distinctions in $v_{2}\{4\}/v_{2}\{2\}$ ratios. Particularly, compact clusters enhance fluctuations leading to significant modifications in these flow harmonics, emphasizing the critical role of compactness in altering fluctuation dynamics.
3. Pearson Correlation Coefficients: The correlations between flow harmonics and mean transverse momenta represented by the Pearson correlation coefficients $\rho(v_{2}^{2}, [p_{\rm T}])$ and $\rho(v_{3}^{2}, [p_{\rm T}])$ exhibit strong sensitivities to cluster configurations. This work demonstrates varied behaviors based on the compactness of clusters, offering a precise probe for structural configurations.

Implications and Future Directions

The implications of this research are twofold. Practically, the findings suggest enhanced sensitivity of certain flow and momentum observables to nuclear structuring, making them potential tools for probing nuclear configurations in experimental settings. Theoretically, the paper provides insights into nuclear interactions and the properties of strong forces within clustered systems.

Furthermore, the differentiation between various models and predictions highlights the necessity of refined theoretical models incorporating realistic nuclear structures for accurate predictions. As RHIC and LHC experiments progress, such explorations can yield rich datasets that would further illuminate $\alpha$ clustering effects.

Conclusion

In conclusion, the paper "Exploring the Compactness of α Cluster in $^{16}$O Nuclei with Relativistic $^{16}$O+$^{16}$O Collisions" stands as a meticulous examination of nuclear structure effects in high-energy collisions. By identifying observable sensitivities to α cluster compactness, the research provides pivotal insights, laying the groundwork for future experimental validations and theoretical investigations into the nuances of nuclear clustering and its implications in particle physics.