Mass of D*_sJ(2317) and Coupled Channel Effect

The resonance D*_sJ (2317) which is considered to be the 1^3P_0 state composed of charm and strange quarks has been discovered recently. The measured mass, which is about 160 MeV lower than the mass of the 1^3P_0 state obtained from the potential model calculation by Godfrey and Isgur, was considered surprisingly low and attracted a lot of theoretical investigations. We calculate the mass shift of the 1^3P_0 state by using the coupled channel e#ect. Our result shows that the coupled channel e#ect naturally explains the low mass of D*_sJ (2317).