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Seminario Christian Weiss
julio 19, 2019 @ 11:00 am
Lugar: Seminario de Física Teórica 2ª planta
Ponente: Christian Weiss (Jefferson Lab)
Titulo: “Partonic angular momentum in the nucleon’s chiral periphery”
Resumen: Explaining how the nucleon spin arises from the motion of quarks and gluons is an essential step in understanding hadrons as emergent phenomena of Quantum Chromodynamics. We report about a recent study of the nucleon’s partonic angular momentum content at peripheral transverse distances b ~ 1/M_pi, where the structure is governed by chiral dynamics. We compute the nucleon form factors of the energy-momentum tensor in chiral effective field theory (ChEFT) and construct the transverse densities of angular momentum at fixed light-front time. We find that in the periphery the spin density is suppressed, and the angular momentum is predominantly orbital. In the first-quantized representation of ChEFT in light-front form, the field-theoretical angular momentum density coincides with the
quantum-mechanical orbital angular momentum density of the soft pions in the nucleon’s periphery, resulting in a simple picture of peripheral nucleon structure. The approach presented here can be extended to compute other quantities of peripheral nucleon structure, such as the transverse charge and current densities and the generalized parton distributions (GPDs).