The Calculation And Discussion On The Branch Ratio Of B~0→ρ~+ρ~-

This thesis calculates concretely the branch ratio of B0→ρ+ρ-by the quantum color dynamics factorization method and compares with the experimental data.The quantum color dynamics factorization method is leading in the two-body decay of B meson.The innovation point of this thesis is that based on the work of Mohammadi and Mehraban who have calculated the long-life π D K,we try to take the similar quantum color dynamics factorization method to make the element of matrix and calculate the branch ratio of B meson is much less than the experimental data,while it is better to match with the experimental data if the three final state weak interactions are added,but it still exists distance.Because the numerical value is in the same order magnitude,it shows that the method is also suitable for the short-life particle in the decay of B meson.In most references,a ready-made result for the branch ratio of B0→ρ+ρ-can’t be found directly.This thesis checks that whether the quantum color dynamics factorization method is suitable for the short-life branch ratio of the final state particle,our calculation gives that the result is reasonable to the experimental data considering the twice decay process and the final state weak interactions then it shows the method is suitable.