Results on meson-meson scattering at large $N_{\text{c}}$

We present results on the large $N_{\text{c}}$ scaling of meson-meson scattering amplitudes. We work in a theory with $N_{\text{f}}=4$ degenerate quark flavors and run lattice simulations with $N_{\text{c}}=3-6$ and pion mass $M_{\pi }\approx 590$ MeV. We focus on three different scattering channels, two of which have the same quantum numbers as some tetraquark candidates recently found at LHCb. Finite-volume energies are extracted using a large set of operators, containing two-particle operators corresponding to two pions or two vector mesons, and local tetraquark operators. Using Lüscher’s quantization condition, we constrain the infinite-volume scattering amplitudes and investigate subleading $N_{\text{c}}$ corrections to the large $N_{\text{c}}$ limit. For one of the channels, we find indications of a virtual bound state at $N_{\text{c}}=3$, which may be related to one of the aforementioned exotic states.