B_s-anti-B_s Mixing in Z' Models with Flavor-Changing Neutral Currents
  In models with an extra U(1)' gauge boson family non-universal couplings to the weak eigenstates of the standard model fermions generally induce flavor-changing neutral currents. This phenomenon leads to interesting results in various B meson decays, for which recent data indicate hints of new physics involving significant contributions from b -> s transitions. We analyze the B_s system, emphasizing the effects of a Z' on the mass difference and CP asymmetries. 
Vernon Barger, Cheng-Wei Chiang, Jing Jiang, and Paul Langacker