Speaker
Hanna Grönqvist
(Institut de physique théorique, CEA Saclay)
Description
The observation of a non-zero $v_n\{4\}$ in systems where anisotropic
flow is solely due to fluctuations ($v_2\{4\}$ in p+Pb collisions,
$v_3\{4\}$ in Pb+Pb collisions) implies that initial eccentricity
($\varepsilon_n$) fluctuations are not Gaussian.
This is confirmed by simulations using various initial-state models.
It has been argued that non-Gaussianities may not reflect underlying
microscopic dynamics. On the contrary, there are indications that they
are to a large extent
universal and arise from the global condition $|\varepsilon_n|<1$.
On the other hand, systematic investigations of second and
fourth-order cumulants $\varepsilon_n\{2\}$ and $\varepsilon_n\{4\}$
reveal deviations from this universal behavior in large systems,
which suggests that non-Gaussianities may carry non-trivial dynamical
information.
In this talk, we present results from Monte Carlo simulations and
analytic calculations which we have done in order to
investigate what non-Gaussianities tell us about the early stage of
heavy-ion collisions.
We find that the non-Gaussianities are essentially universal in p+Pb
collisions, but not in large systems like Pb+Pb collisions.
We show that the initial density field has intrinsic non-Gaussianities
(in particular a non-trivial 3-point function) which are instrumental
in explaining experimental observations.
| On behalf of collaboration: | NONE |
|---|
Primary author
Hanna Grönqvist
(Institut de physique théorique, CEA Saclay)
Co-authors
Dr
Jean-Paul Blaizot
(Institut de Physique Theorique, CEA, Saclay)
Jean-Yves Ollitrault
(CNRS)
