Speaker
Description
The second-order shape phase transition of the Xe isotope chain, predicted to lie around $^{128}\text{Xe}$ to $^{130}$Xe, is challenging to measure in low-energy nuclear experiments. Recently, heavy-ion collisions have demonstrated their potential as an imaging tool for nuclear structure by examining anisotropic flow and its correlations with the mean transverse momentum. Hints of a triaxial structure in $^{129}$Xe have been found experimentally and theoretically using these methods; however, these studies were limited to exploring the first moment of the $\gamma$ distribution and could not distinguish between a rigid rotor and $\gamma$-soft nuclei.
In this talk, a comprehensive study of the quadrupole deformation, nuclear diffuseness, and triaxial structure of $^{129}$Xe is presented through investigations of various anisotropic flow and mean transverse momentum observables. Additionally, the $\gamma$-soft structure of the $^{129}$Xe nuclei is investigated experimentally for the first time in heavy-ion collisions using a novel six-particle normalized cumulant, $ NC(v_2^4, \delta p_{\rm T}^2) $, which correlates the fourth moment of the elliptic flow, $ v_2^4$, with the fluctuations of the mean transverse momentum, $ \delta p_{\rm T}^2 $. This correlation is measured in Xe–Xe collisions at $ \sqrt{s_{\rm NN}} = 5.44$ TeV against the baseline of spherical Pb nuclei in Pb–Pb collisions at $ \sqrt{s_{\rm NN}}$ = 5.02 TeV using the ALICE experiment at the LHC. Comparisons with calculations from state-of-the-art models, both with and without fluctuating shape parameters, provide a high-precision probe of the nuclear structure of $^{129}$Xe and facilitate the discovery of the nuclear shape phase transition.
| Category | Experiment |
|---|---|
| Collaboration (if applicable) | ALICE |
