Speaker
Description
One of the challenges of both nuclear and hadronic physics is to fully
understand the structure of nucleons and nuclei through the measurements
of its structure functions. In particular, possible future experiments at
the EIC are aimed to understand the origin of the spin of the proton. This
requires a proper decomposition of the nucleons total angular momentum
into an orbital motion and intrinsic spin. The most common decompositions
of angular momentum are the Jaffe-Manohar (canonical) and Ji (kinetic)
decompositions, which differ by the so-called "potential angular momentum"
and that depend on how the contributions are attributed to quarks and
gluons.
Even if some lattice calculations has shown that difference between the
decompositions is non-zero, we justify a non-vanishing potential angular
momentum using perturbation theory within a simple scalar diquark model at
two-loop level, and motivate the interpretation of such a difference as
originating from the torque exerted by initial or final state interactions
on the struck quark.
