Abstract
We extend the study of quark spin–orbit correlations in the nucleon to the case of transverse polarization. At the leading-twist level, this completes the spin structure of the quark kinetic energy–momentum tensor. In particular, we revisit the transversity decomposition of angular momentum proposed a decade ago by Burkardt and introduce a new transverse correlation, namely between quark transversity and orbital angular momentum. We also provide for the first time the Wandzura–Wilczek expression for the second Mellin moment of twist-3 transversity generalized parton distributions, along with a new sum rule. Based on lattice calculation results, we conclude that the quark transverse spin–orbit correlation is negative for both up and down flavors, just like in the longitudinal case.
Highlights
Understanding the nucleon spin structure is one of the key questions in hadronic physics
We introduced and discussed the quark transverse spin–orbit correlation, which is a new piece of information characterizing the nucleon spin structure
We showed that this correlation can be expressed in terms of tensor generalized parton distributions, scalar charges and axial-vector charges
Summary
Understanding the nucleon spin structure is one of the key questions in hadronic physics. In a former paper [7], the quark longitudinal spin–orbit correlation was studied in detail by performing a (chiral-even) helicity decomposition of the quark energy–momentum tensor. It has, in particular, been shown that the quark longitudinal spin–orbit correlation can quantitatively be expressed in terms of parton distributions. In particular, been shown that the quark longitudinal spin–orbit correlation can quantitatively be expressed in terms of parton distributions Both current phenomenological extractions based on experimental data and lattice calculations indicate that the quark spin is, in average, opposite to the quark kinetic orbital angular momentum (OAM).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call