Spectroscopy of excited quarkonium states in the light-front quark model*

We investigated the ground state (1 S ), radially excited states (2 S ) and (3 S ), and orbitally excited state (1 P ) for the heavy charmonia ( ) and bottomonia ( ) mesons in the light-front quark model (LFQM). The light-front wave functions have been successful in explaining various physical properties of meson states in the past, especially for the 1 S and 2 S states. However, the radially excited state 3 S and orbitally excited state 1 P have rarely been investigated. In this study, we considered these two excited states and investigated the electromagnetic form factors (EMFFs), charge radii, decay constants, parton distribution functions (PDFs), and the distribution amplitudes (DAs) for the quarkonia system. For the sake of completeness, we also studied the ground and the first excited states of quarkonia mesons. We also illustrated the 3D wave functions for the radially excited states to study their nodal structures.