Bs,d → μ+μ− decays in a flavor changing Z′ model

We study the pure leptonic decays Bs,d → μ+μ− in a Flavor Changing Z' Model. From the recent measurements of the branching ratios s(Bs,d → μ+μ−), we have derived the bounds on the effective μ-μ-Z' lepton coupling BLμμ. We find that, (i) if neglecting the contribution from the right-handed lepton coupling BRμμ, we obtain 1.32 < BLμμ < 3.32; (ii) if considering the contribution from the right-handed lepton coupling BRμμ and setting BLμμ = BRμμ, we obtain 0.99 < BLμμ < 2.19. Our results could be useful for researching Z' effects.