Separating the Impact of Nuclear Skin and Nuclear Deformation in High-Energy Isobar Collisions.

Bulk nuclear structure properties, such as radii and deformations, leave distinct signatures in the final state of relativistic heavy-ion collisions. Isobaric collisions offer an easy route to establish explicit connections between the colliding nuclei's structure and the observable outcomes. Here, we investigate the effects of nuclear skin thickness and nuclear deformations on the elliptic flow (v_{2}) and its fluctuations in high-energy ^{96}Ru+^{96}Ru and ^{96}Zr+^{96}Zr collisions. Our findings reveal that the difference in skin thickness between these isobars only influences the inherent ellipticity of the collision systems, v_{2}^{rp}. In contrast, differences in nuclear deformations solely impact the fluctuations of v_{2} around v_{2}^{rp}. Hence, we have identified a data-driven method to disentangle the effects of nuclear skin and nuclear deformations, marking a significant step toward assessing the consistency of nuclear phenomena across energy scales.

Evidence of Quadrupole and Octupole Deformations in

In the hydrodynamic model description of heavy-ion collisions, the elliptic flow v_{2} and triangular flow v_{3} are sensitive to the quadrupole deformation ß_{2} and octupole deformation ß_{3} of the colliding nuclei. The relations between v_{n} and ß_{n} have recently been clarified and were found to follow a simple parametric form. The STAR Collaboration has just published precision v_{n} data from isobaric ^{96}Ru+^{96}Ru and ^{96}Zr+^{96}Zr collisions, where they observe large differences in central collisions v_{2,Ru}>v_{2,Zr} and v_{3,Ru}

Impact of Nuclear Deformation on Relativistic Heavy-Ion Collisions: Assessing Consistency in Nuclear Physics across Energy Scales.

In the hydrodynamic framework of heavy-ion collisions, elliptic flow v_{2} is sensitive to the quadrupole deformation ß of the colliding ions. This enables one to test whether the established knowledge on the low-energy structure of nuclei is consistent with collider data from high-energy experiments. We derive a formula based on generic scaling laws of hydrodynamics to relate the difference in v_{2} measured between collision systems that are close in size to the value of ß of the respective species. We validate our formula in simulations of ^{238}U+^{238}U and ^{197}Au+^{197}Au collisions at top Relativistic Heavy Ion Collider (RHIC) energy, and subsequently apply it to experimental data. Using the deformation of ^{238}U from low-energy experiments, we find that RHIC v_{2} data implies 0.16≲|ß|≲0.20 for ^{197}Au nuclei, i.e., significantly more deformed than reported in the literature, posing an interesting issue in nuclear phenomenology.

Away-side asymmetry of jet correlation relative to the reaction plane: a sensitive probe for jet in-medium modifications.

We propose a new observable based on two-particle azimuth correlation to study the away-side medium response in midcentral Au+Au collisions. We argue that a left-right asymmetry may appear at the away side by selecting triggers separately in the left and right sides of the reaction plane. A simple model estimation suggests that the magnitude of such asymmetry could reach 30% with details depending on the medium response mechanisms. This asymmetry, if observed, can help to distinguish competing theoretical models.