Title : Measurements of Correlations between different order flow harmonics in Pb--Pb collisions with the ALICE experiment at the
LHC

Dong Jo Kim for the ALICE Colloboration
 
The collective expansion of the color-deconfined fireball created in ultra-relativistic heavy-ion collisions can map the initial
state of the quark-gluon plasma (QGP) to the final-state particle spectrum.
Due to quantum fluctuations of the positions of the constituents inside the colliding nuclei, the density of produced QGP is
highly inhomogeneous in the plane transverse to the beam direction and fluctuates from event to event, even for collisions with
identical impact parameters.
Such inhomogeneities in the initial density lead to development of anisotropic pressure gradients, causing an anisotropic
collective expansion of the fireball whose anisotropic flow magnitudes $v_n$ and associated symmetry planes $\Psi_n$ fluctuate
from collision to collision.
The magnitudes of higher-order harmonics are sensitive to the shear viscosity to entropy density ratio [1]. Further, the
correlations between magnitudes of two different flow harmonics can give valuable additional insights to constrain initial
conditions and the transport properties of the system produced in heavy-ion collisions.
Both the magnitudes of individual flow harmonics and the correlations between magnitudes of two different flow harmonics have
been investigated with the ALICE detector at the LHC.
The results will be compared to the calculations from AMPT and hydrodynamic models.

[1] Nucl.Phys. A904-905 (2013) 377c-380c