Study Of ?'???? Within The Framework Of Chiral Perturbation Theory

The decay of ??is an important research topic,which can help us have a better understanding of Chiral Perturbation Theory(Ch PT). Chiral Perturbation Theory based on the global symmetry of Quantum Chromodynamics(QCD) is an effective theory on the low energy QCD.It provides a model-independent description of QCD in the low energy region. In this thesis,we study the decay of ??? ??? in the framework of the Ch PT and in the large Nc expansion in QCD.First,at the leading order,we calculate the decay width.We find that the contribution of this order is very small,indicating that the higher orders of this decay have a bigger impact.Than,at the next-to-leading order,we calculate the decay width,the ? pole and study the ?- ??mixing and Dalitz plot parameters.In addition,we find that at the next-to-leading order, the ?pole agrees with the results from the more strict dispersive analyses. We find that the loop contributions are important in this decay.