Generalized Casimir forces in non-equilibrium systems
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)Abstract
In the present work we propose a method to determine fluctuation induced forces
in non equilibrium systems. These forces are the analogue of
the well known Casimir forces, which were originally introduced in Quantum
Field theory and later extended to the area of Critical Phenomena.
The procedure starts from the observation that many non equilibrium systems
exhibit long-range correlations and the associated structure factors
diverge in the long wavelength limit. The introduction of external bodies
into such systems in general modifies the spectrum of these fluctuations
and leads to the appearance of a net force between these bodies.
The mechanism is illustrated by means of a simple example:
a reaction diffusion equation, where the correlation
function has a characteristic length. The role of this length in the Casimir force is elucidated. Finally, the predictions are compared with a granular fluid with similar structure factors.