Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon
  Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. Here we focus on two twist-2 GTMDs which are denoted by $F_{1,4}$ and $G_{1,1}$ in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of $F_{1,4}$ and $G_{1,1}$ has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the two GTMDs in the scalar diquark model and in the quark-target model, where we also explicitly check the relation to orbital angular momentum. In addition, we compute $F_{1,4}$ and $G_{1,1}$ at large transverse momentum in perturbative Quantum Chromodynamics and show that they are nonzero. 
K. Kanazawa (Niigata U. & Temple U.), C. Lorc\'e (Orsay, IPN &   Li\`ege, IFPA), A. Metz (Temple U.), B. Pasquini (Pavia U. ...
hep-ph hep-ex