New physics effects inB→K(*)ννdecays

We present a model-independent analysis of exclusive rare $B$ decays, $\overrightarrow{B}{K}^{\left(*\right)}\nu \nu .$ The effect of possible new physics is written in terms of dimension-6 four-Fermi interactions. The lepton number violating scalar- and tensor-type interactions are included, and they induce $\overrightarrow{B}{K}^{\left(*\right)}\nu \nu \left(\overline{\nu }\overline{\nu }\right)$ decays. We show systematically how the branching ratios and missing mass-squared spectrum depend on the coefficients of the four-Fermi interactions.