title: Directed flow at midrapidity in heavy-ion collisions.
abstract: It was recently shown that fluctuations in the initial geometry of a heavy-ion collision generally result in a dipole asymmetry of the distribution of outgoing particles. This asymmetry, unlike the usual directed flow, is expected to be present at a wide range of rapidity--including midrapidity. The first evidence of this phenomenon can be seen in recent two-particle correlation data by the STAR Collaboration, providing the last element necessary to quantitatively describe long-range dihadron correlations. We extract differential directed flow from these data and propose a new direct measurement.
authors.affiliation: CEA, IPhT, Institut de physique théorique de Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: Matthew
authors.initials: M
authors.lastname: Luzum
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Ollitrault