title: Longitudinal coherence in a holographic model of asymmetric collisions.
abstract: As a model of the longitudinal structure in heavy ion collisions, we simulate gravitational shock wave collisions in anti-de Sitter space in which each shock is composed of multiple constituents. We find that all constituents act coherently, and their separation leaves no imprint on the resulting plasma, when this separation is ≲0.26/T_{hyd}, with T_{hyd} the temperature of the plasma at the time when hydrodynamics first becomes applicable. In particular, the center-of-mass of the plasma coincides with the center-of-mass of all the constituents participating in the collision, as opposed to the center-of-mass of the individual collisions. We discuss the implications for nucleus-nucleus and proton-nucleus collisions.
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Casalderrey-Solana
authors.affiliation: Instituut voor Theoretische Fysica, Universiteit van Amsterdam, Science Park 904, 1090 GL Amsterdam, The Netherlands.
authors.forename: Michal P
authors.initials: MP
authors.lastname: Heller
authors.affiliation: Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain and Departament de Física Fonamental, Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Mateos
authors.affiliation: Institute for Theoretical Physics and Institute for Subatomic Physics,Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
authors.forename: Wilke
authors.initials: W
authors.lastname: van der Schee