Three-body study of the Tcc⁺ from lattice QCD

We discuss an ongoing first lattice study of the doubly-charmed tetraquark Tcc⁺(3875) via a three-body approach. We investigate the DDπ system in the $I=0$, $C=2$ sector, where the Tcc⁺ appears as a pole in the JP = 1⁺ DDπ elastic scattering amplitude. The approach automatically incorporates two-body DD^* and three-body DDπ effects and treats left-hand cuts due to single π exchanges. Two CLS ensembles, X252 and X253, with pion mass M_π ≈ 280 MeV, are used, and an operator set comprised of two- and three-hadron and tetraquark operators is employed to extract finite-volume energies. Additional inputs are required for the three-body finite-volume analysis, in the form of amplitudes for the $I=1$ $DD$ and $I=1/2$ Dπ two-body subsystems. We present preliminary results for these subchannels and perform exploratory three-body spectra determinations for simple choices of the three-particle K-matrix Kdf, 3, allowing a first comparison to the lattice spectrum.