Experimental review on Light Meson Spectroscopy

The hadron spectrum provides crucial insights into the strong force dynamics, the quark confinement and the transition from quarks and gluons to observable particles. While hadrons’ quark composition is well understood, most of their mass arises from the binding force among quarks —a largely unexplored domain that has driven extensive experimental efforts for decades. Meson spectroscopy serves as a key tool for studying quark interactions and gluon dynamics, enabling the identification of conventional mesons and the search for exotic states such as multiquark aggregates, hybrids, and glueballs. Exotic quantum numbers offer unique discovery opportunities, but many observed candidates exhibit conventional signatures, complicating interpretation due to their broad widths and overlapping decay patterns. This review examines recent progress in light meson spectroscopy, focusing on hadrons composed of light quarks (u, d, s) with masses below 2.2 GeV/𝑐2. It highlights results from various production processes, including 𝑒+𝑒− and nucleon-antinucleon annihilation, hadron scattering, and electro- and photoproduction. Recent advances in analysis techniques and lattice QCD have provided powerful new tools to unravel these complex phenomena, deepening our understanding of the strong interaction and QCD non-perturbative regime.