The T+cc exotic state and its doubly bottom B(*)(s)B(*)(s) counterparts

Abstract

We have studied the exotic doubly charmed D*D system providing a natural explanation for the peak recently observed by LHCb, in terms of D*+D0 and D*0D+ with isospin I = 0. The width has been evaluated accurately based on the decay widths of the D* states. The D0D0π+ decay mode of the bound state formed is studied in detail, showing a narrow peak below the D*+D0 threshold and some strength above it, as observed in the experiment. The remarkable agreement of this approach and the latter experimental analysis supports strongly the molecular nature of this state, the first example of a meson with two open charmed quarks. This study can be naturally extended to the bottom sector giving interesting features for the B(*)(s)B(*)(s) counterparts found there. In addition, our previous study on the D*D* molecular state has been revisited taking into account the insights extracted from the Tcc state and the new results are included in the present manuscript.