Remarks on the process γγ→νν̄ in astrophysics

We discuss the astrophysical consequences of the process γγ→νν̄, when this reaction is mediated by either Majorons or composite neutral leptons, and present the constraints on their coupling coming from stellar energy loss arguments. We also discuss the effect of nuclear absorption when this reaction is mediated by pions, and show that no significant output of energy is provided in this case. Finally, we comment on the importance of these processes in cosmology. © 1995 The American Physical Society.