Extraction of the CKM angle γ from the new “mixed” system of B⁺→π⁺K⁰ and B_d⁰→π⁰K⁰ decays

In this paper we try to extract the Cabibbo-Kobayashi-Maskawa angle γ from the new “mixed” system of B⁺→π⁺K⁰ and B_d⁰→π⁰K⁰ decays. We also update the constraints on the angle γ from the observables R and A₀. In the parametrization, the SU(2) isospin symmetry of strong interactions is applied. We find the following results: (a) the measured value of R is now very close to unity, the bound on the angle γ from the measurement of R is therefore not as promising as before, but some bounds on γ can still be read off from the r-γ plane if r could be fixed by using an additional input; (b) the measured R₁ implies a limit on the strong phase Δ₁; (c) due to the contribution from the color allowed electroweak penguin amplitude, the minimal value of R₁ can be larger than unity. For ε₁=0.2 and R₁=1.2, the range of 65°<~γ<~115° will be excluded, such bounds on γ are interesting and complimentary to the limits from global fit; and (d) the dependences of extraction of γ on the variation of parameters ε₁, ρ, and r₁ and strong phases are also studied.