The impact of excited neutrinos on $\nu \bar{\nu}\to \gamma\gamma$
  process
  We examine the effect of excited neutrinos on the annihilation of relic
neutrinos with ultra high energy cosmic neutrinos for the $\nu \bar{\nu}\to
\gamma\gamma$ process. The contribution of the excited neutrinos to the
neutrino-photon decoupling temperature are calculated. We see that
photon-neutrino decoupling temperature can be significantly reduced below the
obtained value of the Standard Model with the impact of excited neutrinos.
