New physics contributions to B¯s→π0(ρ0)η(′) decays

The decay modes B¯s→π0(ρ0)η(′) are dominated by electroweak penguins that are small in the standard model. In this work we investigate the contributions to these penguins from a model with an additional U(1)′ gauge symmetry and show there effects on the branching ratios of B¯s→π0(ρ0)η(′) . In a scenario of the model, where Z′ couplings to the left-handed quarks vanish, we show that the maximum enhancement occurs in the branching ratio of B¯s0→π0η′ where it can reach 6 times the SM prediction. On the other hand, in a scenario of the model where Z′ couplings to both left-handed and right-handed quarks do not vanish, we find that Z′ contributions can enhance the branching ratio of Bs0→ρ0η up to one order of magnitude comparing to the SM prediction for several sets of the parameter space where both ΔMBs and Sψϕ constraints are satisfied. This kind of enhancement occurs for a rather fine-tuned point where the ΔMBs constraint on ∣SSM(Bs)+SZ′(Bs)∣ is fulfilled by overcompensating the SM via SZ′(Bs)≃-2SSM(Bs) .