Analysis of the doubly-charmed tetraquark molecular states with the QCD sum rules

In the present work, we investigate the scalar, axialvector and tensor doubly-charmed tetraquark molecular states without strange, with strange and with doubly-strange via the QCD sum rules, and try to make assignment of the T${}_{cc}^{+}$ from the LHCb collaboration in the scenario of molecular states. The predictions favor assigning the T${}_{cc}^{+}$ to be the lighter DD* molecular state with the spin-parity J${}^P$=1${}^{+}$ and isospin I=0, while the heavier DD* molecular state with the spin-parity J${}^P$=1${}^{+}$ and isospin I=1 still escapes experimental detections, the observation of the heavier DD* molecular state would shed light on the nature of the T${}_{cc}^{+}$. All the predicted doubly-charmed tetraquark molecular states can be confronted to the experimental data in the future.