Determining the meson spectrum directly from Quantum Chromodynamics (QCD) remains a central challenge, since QCD is strongly coupled at low energies and most excited states appear as resonances in hadronic decay channels. A recent review surveys advances in lattice QCD and scattering theory that now make it possible to extract meson spectra and resonance properties from first principles.

The paper reviews the current state of the art in lattice QCD meson spectroscopy, a programme that aims to describe both bound and resonant states in a systematic way. Among the most active frontiers are the extraction of resonant and coupled-channel amplitudes, which describe how a meson can decay into several hadrons simultaneously.

The review also highlights recent developments in three-body dynamics and in the determination of meson photo-couplings, two ingredients needed to connect theory with photoproduction experiments and collider data. These advances make it possible to treat broad resonances and states lying near two- and three-hadron thresholds, where traditional approaches fail.

Together, these advances are bringing the community closer to a comprehensive first-principles description of the excited meson spectrum, without relying on phenomenological models. Consolidating three-body techniques and comparing lattice predictions with experimental measurements at future facilities remain open tasks.