Constraints on flavor-changing Z′ models by Bs mixing, Z′ production, and Bs→μ+μ−

Certain string-inspired Z′ models have non-universal interactions to three families of fermions and induced tree-level flavor-changing couplings. We use recent results on Bs-B¯s mixing to constrain the size of the flavor-changing couplings in the b-s sector. In some highly predictive Z′ models, such a constraint on b-s coupling can be translated into the flavor-diagonal couplings. Based on the Z′ production limits at the Tevatron, we obtain the limit on the leptonic couplings of Z′ and then make predictions for Bs→μ+μ− branching ratios. We conclude that with the present constraints from Bs mixing and Z′ production, the muonic decay of Bs may not be observed at the Tevatron if the projected integrated luminosity is about O(5-10)fb−1.