  We present a new model to identify natural fluctuations in fluids, allowing
us to describe localization phenomena in the transport of electrons, positrons
and positronium through non-polar fluids. The theory contains no free
parameters and allows for the calculation of capture cross sections
$\sigma_{cap}(\epsilon)$ of light-particles in any non-polar fluid, required
for non-equilibrium transport simulations. We postulate that localization
occurs through large shallow traps before stable bound states are formed. Our
results allow us to explain most of the experimental observations of changes in
mobility and annihilation rates in the noble gases and liquids as well as make
predictions for future experiments. Quantities which are currently inaccessible
to experiment, such as positron mobilities, can be obtained from our theory.
Unlike other theoretical approaches to localization, the outputs of our theory
can be applied in non-equilibrium transport simulations and an extension to the
determination of waiting time distributions for localized states is straight
forward.

Computational Physics;Statistical Mechanics