  We consider two interacting particles on the circle. The particles are
subject to stochastic forcing, which is modeled by white noise. In addition,
one of the particles is subject to friction, which models energy dissipation
due to the interaction with the environment. We show that, in the diffusive
limit, the absolute value of the velocity of the other particle converges to
the reflected Brownian motion. In other words, the interaction between the
particles are asymptotically negligible in the scaling limit. The proof
combines averaging for large energies with large deviation estimates for small
energies.
