  A degenerate fourth-order parabolic equation modeling condensation phenomena
related to Bose-Einstein particles is analyzed. The model is a
Fokker-Planck-type approximation of the Boltzmann-Nordheim equation, only
keeping the leading order term. It maintains some of the main features of the
kinetic model, namely mass and energy conservation and condensation at zero
energy. The existence of a local-in-time nonnegative continuous weak solution
is proven. If the solution is not global, it blows up with respect to the
$L^\infty$ norm in finite time. The proof is based on approximation arguments,
interpolation inequalities in weighted Sobolev spaces, and suitable a priori
estimates for a weighted gradient $L^2$ norm.
