Relations among TMDs in the Parton Model *

Transverse momentum dependent parton distribution functions (TMDs) play an important role for the description of deep-inelastic scattering processes, and constitute important parts of the experimental programs at BNL, Jefferson Lab and the future Electron-Ion Collider. While some TMDs are well-studied, much less is known about other TMDs. One helpful guideline in this situation is the use of models like the covariant parton model, which predicts many interesting relations among different TMDs. In this contribution, we report results of a study of the relations among TMDs in the covariant parton model.