Work

Investigation of an octupole breathing mode of Pb 208 as a resolution to the elliptical-to-triangular azimuthal anisotropy puzzle in ultracentral relativistic heavy ion collisions

Year: 2025

Type: article

Abstract: Relativistic heavy ion collisions provide a unique opportunity to probe the nuclear structure by taking an instantaneous snapshot of the colliding nuclei and converting it into momentum anisotropies of final emitted hadrons. A long-standing puzzle of too large a ratio of the elliptical-to-triangular (${v}_{2}$-to-${v}_{3}$) anisotropies in ultracentral $^{208}\mathrm{Pb}+^{208}\mathrm{Pb}$ collisions at the Large Hadron Collider (LHC) cannot be solved simply by hydrodynamic simulations with initial conditions containing the spherical or certain deformed shape of $^{208}\mathrm{Pb}$. In this Letter, using the iEBE-VISHNU relativistic viscous hydrodynamic hybrid model simulations with the ${\mathrm{T}}_{\mathrm{R}}\mathrm{ENTo}$ initial condition, we show that a dynamic octupole deformation---a shape-breathing mode of $^{208}\mathrm{Pb}$---could potentially solve the ${v}_{2}$-to-${v}_{3}$ puzzle and simultaneously describe the ${v}_{3}{4}$ data measured in experiment. Our results highlight the unique capability of capturing transient collective properties of nuclei on yoctosecond (${10}^{\ensuremath{-}24}$ s) timescales, unfeasible with low-energy nuclear reactions.

Source: Physical Review C

DOI: 10.1103/r39l-dwpp

Authors: Hao-jie Xu, Duoduo Xu, Shujun Zhao, Wenbin Zhao, Huichao Song, Fuqiang Wang