Analysis of Tcc and Tbb based on the hadronic molecular model and their spin multiplets

Tcc(ccu¯d¯)+ has been reported by the LHCb experiment in 2022. The analysis using the Breit-Wigner parametrization found the small binding energy, 0.273 MeV, which is measured from the threshold of D*+D0. In this paper, we consider Tcc as a DD* hadronic molecule as a deuteronlike state. The one-boson exchange model is employed as for the heavy meson interactions, where we determine the cutoff parameter Λ to reproduce the reported binding energy of Tcc with I(JP)=0(1+). We discuss the properties of the bound state and also search for Tcc with quantum numbers other than 0(1+). Furthermore, we analyze Tbb as a bottom counterpart of Tcc, which involves two bottom quarks, and obtain several bound states. Finally, we consider the light-cloud basis for wave functions of the doubly heavy tetraquarks in the heavy quark limit. Using the basis, we find the spin multiplets of their bound states, indicating the spin structures of diquarks in Tcc and Tbb with the finite quark masses.