  We present the first complete parametrization for the matrix elements of the
generic light-front gauge-invariant energy-momentum tensor, derive the
expressions giving separately the spin and orbital angular momentum of quarks
and gluons as probed in high-energy scattering experiments, and discuss the
relations with two-parton generalized and transverse-momentum dependent
distributions. As a by-product, we recovered the Burkardt sum rule, clarified
its physical meaning and obtained similar new sum rules for higher-twist
distributions.
