Exploring meson structure through the light-front quark model

Understanding how mesons emerge from the underlying dynamics of quarks and gluons remains a fundamental problem in nonperturbative quantum chromodynamics (QCD). Light-front dynamics offers a natural framework for this purpose, providing boost-invariant descriptions of hadrons and enabling direct connections between theory and experimentally measurable observables. Within this approach, the light-front quark model (LFQM) has emerged as a particularly effective tool for studying meson structure. This brief review summarizes recent progress in light-front quark model (LFQM) studies of meson structure. Emphasis is placed on three main directions: (i) the construction of realistic light-front wave functions that incorporate essential hadron dynamics, including excited states; (ii) advances in addressing issues of covariance and current conservation in light-front calculations, leading to more consistent and reliable predictions; and (iii) studies of how meson properties are modified in extreme environments such as nuclear matter and strong magnetic fields. These developments underscore the versatility of the LFQM and its growing role in deepening our understanding of mesons and the nonperturbative regime of QCD.