gamma nu -> gamma gamma nu and crossed processes at energies below m_W

Abstract

The cross sections for the processes $γν\to γγν$, $γγ\toγν\barν$ and $ν\barν\toγγγ$ are calculated for a range of center of mass energies from below $m_e$ to considerably above $m_e$, but much less than $m_W$. This enables us to treat the neutrino--electron coupling as a four--Fermi interaction and results in amplitudes which are electron box diagrams with three real photons and one virtual photon at their vertices. These calculations extend our previous low--energy effective interaction results to higher energies and enable us to determine where the effective theory is reliable.

12 pages, RevTex, 10 postscript figures included