Speaker
Description
During the talk, I will discuss progress in applying the relativistic three-particle scattering formalism of Hansen and Sharpe to systems of non-degenerate mesons of arbitrary angular momenta. For concreteness, I will focus on the $DD\pi$ system in the charm $C=2$ and isospin $I=0$ sectors, where the doubly charmed tetraquark $T_{cc}^+(3875)$ should appear as a pole in the elastic $3 \to 3$ scattering amplitude. After a short overview of the tetraquark physics, finite-volume results, and the three-body formalism, I will describe solutions to the relativistic integral equations describing this three-body process. I will focus on systems with heavier than physical pion masses and present several three-body models of the state proposed to explain the available and future lattice data. In particular, I will advocate for the importance of partial S- and D-wave mixing in this system and describe its implications for the finite-volume $DD\pi$ energy levels.
