Primordial non-Gaussianity in heavy-ion collisions

Understand

We show that experimental data on cumulants of anisotropic flow in heavy-ion collisions probe the non-Gaussian statistics of the energy density field created right after the collision.

• We carry out a perturbative expansion of the initial anisotropies of the system in terms of its density fluctuations.
• We argue that the correlation between the magnitudes of elliptic flow and triangular flow, dubbed $sc(3,2)$, is generically of the same sign and order of magnitude as the kurtosis of triangular flow in a hydrodynamic picture.
• The experimental observation that these quantities are negative implies that the distribution of energy around a given point has positive skew.