Speaker
Description
Angular momentum (AM) contains explicit position vectors, and its definition depends on the choice of pivot. The corresponding internal AM operators defined relative to the relativistic centers of energy, mass, and spin, as well as their transverse spin sum rules, have been studied previously. We extend this discussion to spatial distributions in the nucleon. We derive the two-dimensional distributions in the transverse plane by integrating the corresponding three-dimensional spatial distributions over the longitudinal coordinate within the quantum phase-space formalism. We analyze their multipole structures and investigate how the transverse distortions evolve with the longitudinal nucleon momentum $P_{z}$. We further perform the same analysis in the light-front (LF) formalism with respect to the center of LF momentum. We propose an interpolation relation between instant-form and \ac{LF} spatial distributions, showing that the two formalisms consistently match in the infinite-momentum frame.