Exploring the compactness of α cluster in ^16O nuclei with relativistic ^16O+^16O collisions

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