The chirally-odd twist-3 distribution e(x)

Abstract

Properties of the nucleon twist-3 distribution function e(x) are reviewed. It is emphasized that the QCD equations of motion imply the existence of a delta-function at x=0 in e(x), which gives rise to the pion-nucleon sigma-term. According to the resulting ``practical'' DIS sum rules the first and the second moment of e(x) vanish, a situation analogue to that of the pure twist-3 distribution function ${\bar{g}}_2(x)$.

Comments: 19 pages, 3 figures, new references and figures added