Partonic angular momentum in the nucleon's chiral periphery

Abstract

We study the nucleon's partonic angular momentum (AM) content at peripheral transverse distances $b=\mathcal{O}(M_{\pi }^{-1})$, 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 AM at fixed light-front time. In the periphery the spin density is suppressed, and the AM is predominantly orbital. In the first-quantized representation of ChEFT in light-front form, the field-theoretical AM density coincides with the quantum-mechanical orbital AM density of the soft pions in the nucleon's periphery.

Comments: 6 pages, 2 figures