K_L to γ ν > bar{ν} decay beyond the standard model

The decay $K_L \to \gamma \nu \bar{\nu}$ is investigated beyond the standard model. Interestingly, the upper limit of the CP-conserving and CP-violating branching ratios of the decay, induced from the possible extensions of the standard model, would be larger than the corresponding branching ratios given in the standard model respectively, and it is expected that the CP-violating part could be enhanced.