Gravitational interactions between fast neutrinos and the formation of   bound rotational states
  The gravitational forces exerted between fast neutrinos at short distances are examined using Newton's gravitational law, special relativity, and the equivalence principle. It is found that the magnitude of these forces is not negligible and can lead to the formation of bound rotational states with radii in the fm range. 
Constantinos G. Vayenas and Stamatios Souentie
physics.gen-ph