Mean joint residence time of two Brownian particles in a sphere
  We calculate the mean joint residence time of two Brownian particles in a sphere, for very general initial conditions. In particular, we focus on the dependence of this residence time as a function of the diffusion coefficients of the two particles. Our results can be useful for describing kinetics of bimolecular diffusion controlled reactions activated by catalytic sites. 
O. Benichou, M. Coppey, J. Klafter, M. Moreau and G. Oshanin