Conveners
Parallel Session - Collective dynamics IV
- Yasuyuki Akiba (RIKEN)
The applicability of fluid-dynamical models in the extreme conditions produced in heavy ion collisions has not yet been properly understood from a theoretical point of view. This happens mostly because the derivation of hydrodynamics from microscopic theory often relies on the assumption that the system is sufficiently close to local equilibrium -- something difficult to justify in the rapidly...
The ATLAS collaboration has recently shown that anisotropic flow exhibits a strong centrality dependence in ultracentral collisions [arXiv:1904.04808]. In particular, the 4-particle cumulant of elliptic flow changes sign, and the centrality at which this change of sign occurs depends on the observable which is used to determine the centrality. We show that these features are universal...
One of the primary goals of flow studies in heavy-ion collisions during recent years is a better understanding of the transport properties of the quark-gluon plasma (QGP), such as the temperature dependence of the shear viscosity to entropy density ratio, $\eta/s(T)$. The higher order harmonic flow observables ($n > 3$) and their non-linear response to the initial state anisotropy has the...
Recent measurements and hydrodynamic model calculations suggest that the higher-order flow coefficients, $v_{n}$ (n $>$ 3), have two contributions: a linear contribution driven by the initial-state eccentricities, $\epsilon_{n}$, and a mode-coupled contribution derived from the lower-order eccentricity coefficients $\epsilon_{2}$ and $\epsilon_{3}$. Measurement of these two contributions to...
We propose a new and improved principal component analysis (PCA), which characterizes the fluctuations of anisotropic flow and how these fluctuations are correlated in transverse momentum. Then, using state-of-the-art hydrodynamic simulations, we make an explicit connection between the initial geometry and these principal components. The usual eccentricity scaling of anisotropic flow implies...
To assess the properties of the quark-gluon plasma formed in heavy ion collisions, correlations between the mean transverse momentum, [$p_{T}$], and the magnitude of the flow harmonics, $v_{n}$, are measured by the ATLAS experiment at the LHC. The analysis uses data samples of lead-lead collisions at $\sqrt{s_{NN}} =5.02$~TeV and proton-lead collisions at $\sqrt{s_{NN}} =5.02$~TeV,...
