Testing the non-universal Z′ model in Bs→ϕπ0 decay

The branching ratio and direct CP asymmetry of the decay mode Bs→ϕπ0 have been calculated within the QCD factorization approach in both the standard model (SM) and the non-universal Z′ model. In the standard model, the CP averaged branching ratio is about 1.3×10−7. Considering the effect of Z′ boson, we found the branching ratio can be enlarged three times or decreased to one third within the allowed parameter spaces. Furthermore, the direct CP asymmetry could reach 55% with a light Z′ boson and suitable CKM phase, compared to 25% predicted in the SM. The enhancement of both branching ratio and CP asymmetry cannot be realized at the same parameter spaces, thus, if this decay mode is measured in the upcoming LHC-b experiment and/or Super B-factories, the peculiar deviation from the SM may provide a signal of the non-universal Z′ model, which can be used to constrain the mass of Z′ boson in turn.