2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117686We 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 $B\to M ν\barν$ decays and $Δm_s$. We find that although the latter give much stronger constraints on the coupling than the former, they are complementary to each other.Talk given at Summer Institute 2006, APCTP Pohang Korea, August 23-30, 2006, 5 pages, 4 figures, LateXHigh Energy Physics - Phenomenologytext