Role of $a_0(1710)$ in the $D_s^{+}\to {\rho }^{+}\varphi ,{\rho }^{+}\omega$ decays

Abstract

We look into the $D_s^{+}\to {\rho }^{+}\varphi$ and $D_s^{+}\to {\rho }^{+}\omega$ weak decays recently measured by the BESIII collaboration, which proceed very differently in a first step of the weak decay. While the first reaction proceeds directly via external emission, the second one does not go via external nor internal emission, what prompted the experimental team to claim that it proceeds via $W-$annihilation. We show in this work that the unexpectedly large rate of the $D_s^{+}\to {\rho }^{+}\omega$, should it be due to $W-$annihilation, has a different explanation since is it naturally obtained once final state interaction of the ${\rho }^{+}\varphi ,{\rho }^{+}\omega$ and $K^{\ast +}{\bar{K}}^{\ast 0}$ channels is taken into consideration. The interaction of these channels produces the $a_0(1710)$ resonance, predicted long ago as a molecular state of these coupled channels, and only recently observed, and it is the presence of this resonance what makes the effect of the final state interaction very important in the weak decays and provides a natural explanation of the experimental decay rates.

Comments: 7 pages, 4 figures