Isospin-conserving hadronic decay of the D_s1(2460) into D_sπ⁺π⁻

Abstract

The internal structure of the charm-strange mesons $D_{s0}^*(2317)$ and $D_{s1}(2460)$ are subject of intensive studies.
Their widths are small because they decay dominantly through isospin-breaking hadronic channels $D_{s0}^*(2317)^+\to D_s^+\pi^0$ and $D_{s1}(2460)^+\to D_s^{*+}\pi^0$.
The $D_{s1}(2460)$ can also decay into the hadronic final states $D_s^+\pi\pi$, conserving isospin. In that case there is, however, a strong suppression from
phase space.
We study the transition $D_{s1}(2460)^+\to D_s^+\pi^+\pi^-$ in the scenario that the $D_{s1}(2460)$ is a $D^*K$ hadronic molecule. The $\pi\pi$ final state interaction is taken into account through dispersion relations. 
We find that the ratio of the partial widths of the $\Gamma(D_{s1}(2460)^+\to D_s^+\pi^+\pi^-)/\Gamma(D_{s1}(2460)^+\to D_s^{*+}\pi^0)$ obtained in the
molecular picture is consistent with the existing experimental measurement.
More interestingly, we demonstrate that the $\pi^+\pi^-$ invariant mass distribution shows a double bump structure,
which can be used to disentangle the hadronic molecular picture from the compact state picture for the $D_{s1}(2460)^+$.
Predictions on the $B_{s1}^0\to B_s^0\pi^+\pi^-$ are also made.