πN sigma term and chiral-odd twist-3 distribution function e(x) of the nucleon in the chiral quark soliton model -: art. no. 114002

The isosinglet combination of the chiral-odd twist-3 distribution function e(u)(x)+e(d)(x) of the nucleon has the outstanding properties that its first moment is proportional to the well-known piN sigma term and that it contains a delta-function singularity at x=0. These two features are inseparably connected in that the above sum rule would be violated if there is no such singularity in e(u)(x)+e(d)(x). Very recently, we found that the physical origin of this delta-function singularity can be traced back to the long-range quark-quark correlation of scalar type, which signals the spontaneous chiral symmetry breaking of the QCD vacuum. The main purpose of the present paper is to give complete theoretical predictions for the chiral-odd twist-3 distribution function e(a)(x) of each flavor a on the basis of the chiral quark soliton model, without recourse to the derivative-expansion-type approximation. These theoretical predictions are then compared with the empirical information extracted from the CLAS data of the semi-inclusive DIS processes by assuming the Collins mechanism only. A good agreement with the CLAS data is indicative of a sizable violation of the piN sigma-term sum rule or, equivalently, the existence of a delta-function singularity in e(u)(x)+e(d)(x).