Relativistic dynamics of charmonia in strong magnetic fields

We investigate the properties of charmonium systems in strong external magnetic fields using a relativistic light-front Hamiltonian approach within the Basis Light-Front Quantization (BLFQ) framework. By solving the eigenvalue problem for the invariant mass squared operator with confinement potentials and one-gluon-exchange interactions, we obtain the mass spectrum and wave functions under varying magnetic fields. Our results reveal significant spectral modifications via the Zeeman effect, including $\eta_c$-$J/\psi$ mixing and magnetic sublevel splitting. Momentum density analysis demonstrates wave function deformation, with transverse momentum broadening and longitudinal narrowing under strong fields, alongside structural shifts in parton distributions such as double-hump profiles in excited states. Relativistic corrections and center-of-mass coupling critically drive these dynamics, highlighting the necessity of a relativistic framework for QCD bound states in extreme magnetic environments.