The Theoretical Research For The Decay Of(?) �'D⁺ + K₁

Meson K₁ is P-wave meson. It is difficult to calculate because of its state. Inaddition, K₁ is the mixture of ³P₁ and ¹P₁ states (L (?) S coupling), which makes theproblem even more complicated. Because experiment is partially limited by the theoret-ical research; without the fundamental of theories, it is very hard to fix the method ofmeasurement, only leaving the experimental result of the lowest state for K, i.e. K⁺. Toget out of the stuck of P-wave meson like K₁, consider the mixture of ³P₁ and ¹P₁ statesinside K₁, and obtain the branching ratios of the decay B⁰→D+ + K₁ can make nicebasic for the experimental measurement and provide references to search for the mixtureangle of P-wave meson K₁(1270) and K₁(1400).First of all, the wave functions from Bethe-Salpeter method are the fundamental,including the wave functions of ³P₁ state, ¹P₁ state and 1S0 state. Second, to get theformulae of hardon matrix element for the decay of B⁰→D+ + K₁ simplified is the nextschedule. Third, K₁ can be seen as decay constant approximately, considering its ³P₁ and¹P₁ states mixture inside. Here, it makes use of'the factorization approximation'. Fourth,to make use of Fortran computer programs with appropriate inputting parameters is forbranching ratios. In order to compare conveniently, there is also the calculation for thedecay of B⁰→D(?) + K⁺.In the end, the final branching ratios of decay B⁰→D+ + K₁ is compared to anothertheoretical result from PQCD theory, and is also compared to the experimental result forthe decay of B⁰→D(?) + K⁺. The result is suitable to the expectation, and acceptable inthe bound of errors.