OPEDelta is a lightlike axial vector as used e.g. in the operator product expansion in QCD.
See also: Twist2QuarkOperator.
![[Graphics:Images/index_gr_1.gif]](Images/index_gr_1.gif)
![[Graphics:Images/index_gr_2.gif]](Images/index_gr_2.gif){kind=small}
![[Graphics:Images/index_gr_3.gif]](Images/index_gr_3.gif)
![[Graphics:Images/index_gr_4.gif]](Images/index_gr_4.gif){kind=small}
![[Graphics:Images/index_gr_5.gif]](Images/index_gr_5.gif)
OneLoopSimplify
OPEi![[Graphics:Images/index_gr_6.gif]](Images/index_gr_6.gif){kind=small}