Year: 2012
Type: article
Abstract: We investigate how the initial geometry of a heavy-ion collision is transformed into final flow observables by solving event-by-event ideal hydrodynamics with realistic fluctuating initial conditions. We study quantitatively to what extent anisotropic flow (${v}_{n}$) is determined by the initial eccentricity ${\ensuremath{\varepsilon}}_{n}$ for a set of realistic simulations, and we discuss which definition of ${\ensuremath{\varepsilon}}_{n}$ gives the best estimator of ${v}_{n}$. We find that the common practice of using an ${r}^{2}$ weight in the definition of ${\ensuremath{\varepsilon}}_{n}$ in general results in a poorer predictor of ${v}_{n}$ than when using ${r}^{n}$ weight, for $n>2$. We similarly study the importance of additional properties of the initial state. For example, we show that in order to correctly predict ${v}_{4}$ and ${v}_{5}$ for noncentral collisions, one must take into account nonlinear terms proportional to ${\ensuremath{\varepsilon}}_{2}^{2}$ and ${\ensuremath{\varepsilon}}_{2}{\ensuremath{\varepsilon}}_{3}$, respectively. We find that it makes no difference whether one calculates the eccentricities over a range of rapidity or in a single slice at $z=0$, nor is it important whether one uses an energy or entropy density weight. This knowledge will be important for making a more direct link between experimental observables and hydrodynamic initial conditions, the latter being poorly constrained at present.
Source: Physical Review C
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2044563055