Xiao, YuyangXu, Zhen-NiYao, Zhao-QuianRoberts, Craig D.Rodríguez Quintero, José2026-05-142026-05-142026Xiao (肖宇洋), Y.-Y., Xu (徐珍妮), Z.-N., Yao (姚照千), Z.-Q., Roberts, C. D., & Rodríguez-Quintero, J. (2026). Orbital angular momentum in the pion and kaon: Rest-frame and light-front. Physics Letters B, 876, 140361. https://doi.org/10.1016/j.physletb.2026.1403610370-26931873-2445 (electrónico)https://hdl.handle.net/10272/28326Orbital angular momentum (OAM) is not a Poincaré invariant quantity; so, its value is observer dependent. Notwithstanding that, in quantum chromodynamics, a Poincaré-invariant theory, OAM is part of every hadron wave function. Using continuum Schwinger function methods, we elucidate both the subjective character of in-hadron OAM and expose some of its impacts on pion and kaon structure and observables. For instance, working with light-front projections of their Bethe-Salpeter wave functions, it is found that the pion is a roughly 50/50 mix of light-front OAM zero and one components and the kaon is a 60/40 system. The overall picture is that (near) Nambu-Goldstone modes are complex bound states, each with significant intrinsic OAM, independent of the observer’s reference frame. This feature must be accounted for in the calculation of observables. Inductively, the same is true for all hadrons.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Dyson-Schwinger equationsLight-front wave functionsOrbital angular momentumPion and kaon structurePoincaré covarianceQuantum chromodynamicsjournal article10.1016/j.physletb.2026.140361open access2208.07 Física de Partículas