- '[@Wakamatsu11B]'
- '[@Cho10A]'
- '[@Cho10B]'
- '[@Hatta11]'
- '[@Hatta12]'
- '[@Wong10]'
- '[@Wang10]'
- '[@Sun10]'
- '[@Chen11A]'
- '[@Chen11B]'
- '[@ZhangPak11]'
- '[@LinLiu11]'
- '[@LinLiu12]'
- '[@Chen12]'
- '[@JXZ12]'
- '[@JXY12]'
- '[@Burkardt12]'
- '[@HJL98]'
- '[@Ji11A]'
- '[@Ji11B]'
- '[@Wakamatsu10]'
- '[@Wakamatsu11A]'
- '[@Wakamatsu11B]'
- '[@Cho10A]'
- '[@Cho10B]'
- '[@Hatta11]'
- '[@Hatta12]'
- '[@Wong10]'
- '[@Wang10]'
- '[@ZhangPak11]'
- '[@LinLiu11]'
- '[@Manohar91A]'
- '[@Manohar91B]'
- '[@BB91]'
- '[@BookBLP82]'
- '[@HJL98]'
- '[@MT88]'
- '[@Thomas08]'
- '[@WT05]'
- '[@WN06]'
- '[@WN08]'
- '[@LHPC08]'
title: More on the relation between the two physically inequivalent decompositions of the nucleon spin and momentum
---

OU-HET-745  \

Introduction
============

The nucleon spin puzzle raised by the EMC measurement in 1988 is still one of the fundamental unsolved problems in QCD [@EMC88],[@EMC89]. The current status and homework of the nucleon spin problem can very briefly be summarized as follows. (For recent reviews, see, for example, [@Rev09],[@Rev10].) First, the intrinsic quark spin contribution (or the quark polarization in the nucleon) was fairly precisely determined to be around 1/3 [@COMPASS05]-[@HERMES07]. Second, gluon polarization is likely to be small, although with large uncertainties [@COMPASSG06] -[@STAR06B]. So, what carries the remaining 2/3 of the nucleon spin ? That 