$K_L\to\gamma\nu\bar{\nu}$ in the Light Front Model
  We study the CP conserving and violating contributions to the decay of $\knng$ in the standard model. In our analysis, we use the form factors for $K\to\gamma$ transitions calculated directly in the entire physical range of momentum transfer within the light front model. We find that the branching ratios for the CP conserving and violating parts are about $1.0\times 10^{-13}$ and $1.5\times 10^{-15}$, respectively. 
C.Q. Geng, C.C. Lih, and C.C. Liu