Abstract

Non-equilibrium field theories are an effective description for the spatial and temporal fluctuations of order parameters in complex systems out of equilibrium. Near critical points, their statistics assumes universal shapes and is characterised by few critical exponents. Often, however, the field’s statistics itself is difficult to access experimentally because it requires detailed measurements across large spatial scales. To overcome this limitation, we (theoretically) insert a colloid, i.e. a small particle with a finite interaction radius, into the field. The mutual interaction between the colloid and the field induces memory into the stochastic evolution of the colloid. By way of a diagrammatic perturbation theory, I show how these memory terms can be predicted to leading perturbative order in the coupling strength, and further can be used to infer critical exponents of the surrounding field.