Electroweak Penguin and Leptophobic $Z^\prime$ model

We consider the leptophobic $Z^\prime$ model which can appear naturally in the flipped SU(5) or string-inspired $E_6$ models. This model can be constrained by measurements of the $B\to M \nu\bar{\nu}$ decays and $\Delta m_s$. We find that although the latter give much stronger constraints on the coupling than the former, they are complementary to each other.