Partonic angular momentum in the nucleon's chiral periphery

• Main Authors: C. Granados, C. Weiss
• Format: Article
• Language: English
• Published: Elsevier 2019-10-01
• Series: Physics Letters B
• Online Access: http://www.sciencedirect.com/science/article/pii/S0370269319305611

We study the nucleon's partonic angular momentum (AM) content at peripheral transverse distances b=O(Mπ−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. Keywords: Nucleon spin decomposition, Generalized parton distributions, Energy-momentum tensor, Orbital angular momentum, Chiral effective field theory, Light-front quantization