Decay Constants of D_(sJ)^*(2317) and D_(sJ)(2460)

The resonances $D_{sJ}^*$(2317) and $D_{sJ}$(2460) which are considered to be the $(0^+,1^+)$ doublet composed of charm and strange quarks have been discovered recently. Using the method of Rosner which is based on the factorization hypothesis, we calculate the lower bounds of the decay constants of these states from the branching ratios of $B\to D D_{sJ}$ measured by Belle and Babar.Our result shows that the decay constant of $D_{sJ}$(2460) is about twice that of $D_{sJ}^*$(2317) on the contrary to the naive expectation of the heavy quark symmetry which gives their equality. We show that this big deviation originates from the large internal motion of quarks inside these $P$-wave states and that our result is in good accord with the relativistic quark model calculation.