The Theoretical Calculation For The Branch Ratios Of B_s,d�'γγ Decay

Well-known, rare electromagnetic decays of B mesons are very sensitive to thenew physics，has many contributions of new physics. In the calculation of themeson decay, if the first order is a tree diagram,due to the contribution of higherorder,the contribution of the loop correction will be cover up.In the standardmodel,the contribution of tree diagram has been very accurate fit of theexperimental results.In new physics due to the new vertex coupling constants of thenew particle, thire contribute may be the very embodiment of the first loop diagramor higher Loop. So the calculate of the rare decays, provide an indirect way ofinspection for the standard model or other new physics models.B_s,d�'γγis theprocess like this.Many people have a discuss in the different framework, such as the model withone universal extra dimension and two-higgs-double model. However currently, thestudy ofB_s,d�'γγis immature, there are still a lot of space for reseaching. Beforethe determine of contribution whether comes from new physics, precise calculationin the standard model is necessary. In the framework of the standard model, using acombination of the completely Slapeter and potential model to calculate thebranching ratio. First we obtain initial state meson wave function by theinstantaneous BS equation, according to the low-energy effective theory, theequation of motion theory, we can get the corresponding amplitude. By somemethod of processing loop, we can obtain the numerical solution of the decaybranching finally. The characteristics of our approach is that we consider therelativistic corrections, which makes the calculation more accurate.There are some differences between our results and the results from othermethods and experiment, this is understandable, which is owing to different methods.On the experiment, the detection is more and more precise, less space is left to thenew physics. If we can calculation of the branching ratio more accurate in thestandard model，it will be more credible to the detection of new physics.