Late time evolution of the gravitational wave damping in the early   Universe
  An analytical solution for time evolution of the gravitational wave damping in the early Universe due to freely streaming neutrinos is found in the late time regime. The solution is represented by a convergent series of spherical Bessel functions of even order and was possible with the help of a new compact formula for the convolution of spherical Bessel functions of integer order. 
Gavriil Shchedrin
gr-qc