Speaker
Description
The total spin of a hadron is a complex manifestation of its partonic constituents, arising from both the helicity of quarks and gluons, as well as their orbital angular momenta (OAM). Elucidating this spin structure at the partonic level remains a fundamental challenge in hadron physics. Analogous to spin-orbit correlations in atomic and nuclear systems, the interplay between spin and OAM is also realizable in QCD, adding richer content to the intrinsic spin structure inside hadrons.
In this talk, we will explore spin–orbit correlations in heavy mesons within the framework of light-front dynamics. We begin with a quantum many-body definition and explain its connection to the partonic interpretation. The equivalence between this definition and the expression derived from the parity-odd (P-odd) energy–momentum tensor (EMT) is shown in the valence quark Fock sector. To account for the effects of finite Fock-sector truncation, we analyze the hadron matrix elements of the P-odd EMT and find the relationship between its form factors and the spin–orbit correlation. Finally, we present our numerical results for these quantities in charmonium and the $B_c$ meson, based on light-front wave functions obtained via basis light-front quantization.