On the blow up and condensation of supercritical solution of the   Nordheim equation for bosons
  In this paper we prove that the solutions of the isotropic, spatially homogeneous Nordheim equation for bosons, with bounded initial, data blow up in finite time in the $L^\infty$ norm if the values of the energy and particle density are in the range of values where the corresponding equilibria contains a Dirac mass. We also prove that, in the weak solutions, whose initial data are measures with values of particle and energy densities satisfying the previous condition, a Dirac measure at the origin forms in finite time. 
M. Escobedo and J. J. L. Vel\'azquez
math-ph math.AP math.MP