Cooling of Neutron Stars Revisited: Application of Low Energy Theorems
  Cooling of neutrons stars proceeds mainly via neutrino emission;   As an example we study the modified neutrino bremsstrahlung process $nn \to nn\nu\bar{\nu}.$   The radiated energy is small compared to other scales in the system.   Hence one can use low-energy theorems to compute the neutrino emissivity in terms of the non-radiative process, ie the on-shell $T$ matrix. We find that the use of the $T-$matrix as compared to previous estimates based upon one pion exchange leads a substantial reduction of the predicted emissivity. 
A. E. L. Dieperink, E. N. E. van Dalen, A. Korchin, R. Timmermans