Speaker
Description
Hydrodynamic attractors were first studied in conformal Bjorken flow in the context of heavy ion collisions to discuss how the fireball of strongly interacting matter approaches hydrodynamic behaviour. Recently, a hydrodynamic attractor has also been constructed for the case of ultracold atom gases, meaning it now has a second real world application and may soon be measured directly in experiment. Interestingly, the newly discovered instance of this behaviour has some significant differences to Bjorken flow: it appears in a deeply nonrelativistic, nonconformal and isotropically contracting system. This suggests that the phenomenon is universal to all dynamical systems where equilibration competes with expansion. Through more general studies of how the behaviour plays out in different situations, one might eventually be able to construct an effective dynamical description that would supercede hydrodynamics.
We take a first step in this direction by examining continuous modifications of conformal Bjorken flow. In some scenarios, the competition between equilibration and expansion can play out very differently, even leading to long term stable states of coexistence. We discuss how concepts from the known case transfer to the new case, for example the scaling variable and the distinction between the early time and late time attractors, and propose a modification of how to identify the behaviour that we believe to be a more accurate representation.