Directed flow in ultrarelativistic heavy-ion collisions

Understand

We study the generation of directed flow in the hydrodynamic expansion of the hot matter formed in ultrarelativistic heavy-ion collisions at 200GeV.

• The experimentally observed negative directed flow in a wide range of central pseudorapidities isreproduced assuming that the fireball is tilted away from the collision axis.
• The tilt of the source is consistent with a preferential emission in the forward/backward hemisphere from forward/backward participating nucleons.
• The model reproduces the experimentally observed scaling of the directed flow when going from Au-Au to Cu-Cu systems.