The $T_{c\bar{s}}(2900)$ as a threshold effect from the interaction of the $D^{\ast }{K}^{\ast }$, $D_s^{\ast }\ddot{I}$ channels

Abstract

We look at the mass distribution of the $D_s^{+}\ddot{I}{€}^{-}$ in the $B^0\to {\bar{D}}^0{D}_s^{+}\ddot{I}{€}^{-}$ decay, where a peak has been observed in the region of the $D_s^{\ast }\ddot{I}$, $D^{\ast }{K}^{\ast }$ thresholds. By creating these two channels together with a ${\bar{D}}^0$ in $B^0$ decay and letting them interact as coupled channels, we obtain a structure around their thresholds, short of producing a bound state, which leads to a peak in the $D_s^{+}\ddot{I}{€}^{-}$ mass distribution in the $B^0\to {\bar{D}}^0{D}_s^{+}\ddot{I}{€}^{-}$ decay. We conclude that the interaction between the $D^{\ast }{K}^{\ast }$ and $D_s^{\ast }\ddot{I}$ is essential to produce the cusp structure that we associate to the recently seen $T_{c\bar{s}}(2900)$, and that its experimental width is mainly due to the decay width of the $\ddot{I}$ meson. The peak obtained together with a smooth background reproduces fairly well the experimental mass distribution observed in the $B_0\to {\bar{D}}^0{D}_s^{+}\ddot{I}{€}^{-}$ decay.

5 pages, 8 figures, 1 table