Anisotropic flow in √s = 2.76 TeV Pb + Pb collisions at the LHC

The results on pT-differential elliptic flow in √s = 2.76 TeV Pb + Pb collisions at the Large Hadron Collider (LHC) reported by the ALICE Collaboration are remarkably similar to those for √s = 200 GeV gold-gold collisions at the Relativistic Heavy Ion Collider (RHIC). This result is surprising, given the expected longer lifetime of the system at the higher collision energies. We show that it is nevertheless consistent with (3+1)-dimensional viscous event-by-event hydrodynamic calculations, and demonstrate that elliptic flow at both RHIC and LHC is built up mostly within the first ∼5 fm/c of the evolution. We conclude that an 'almost perfect liquid' is produced in heavy-ion collisions at the LHC. Furthermore, we present predictions for triangular flow as a function of transverse momentum for different centralities.