Nonperturbative origin of the delta-function singularity in the chirally odd twist-3 distribution function e(x) -: art. no. 114011

By making full use of the field theoretical nature of the chiral quark soliton model, we demonstrate that the nonvanishing quark condensate as a signal of the spontaneous chiral symmetry breaking of the QCD vacuum brings about a delta-function singularity at x=0 in the chirally odd twist-3 distribution e(x) of the nucleon. This singularity in e(x), which would be observed as a sizable violation of the 1st moment sum rule, is then interpreted as giving a very rare case that the nontrivial vacuum structure of QCD manifests in an observable of a localized QCD excitation, i.e., the nucleon.