Progress in meson-meson scattering at large Nc

We study the large Nc scaling of meson-meson scattering amplitudes in a theory with Nf=4 degenerate quark flavors. We focus on two different scattering channels, one having the same quantum numbers as some recently found tetraquark states at LHCb. Using Lüscher's formalism, we study the Nc dependence of the scattering phase shift and investigate the presence of exotic resonances in the scattering amplitude. We analyze the impact of including two-vector-meson and tetraquark-like operators to extract the finite-volume energies.