Next-to-leading power endpoint DIS and PDF factorization
We study deep-inelastic scattering (DIS) in the threshold region $x\to 1$ beyond leading power in $1-x$ at leading twist. In the framework of position-space soft-collinear effective theory, we derive a factorization theorem for the off-diagonal parton-scattering channel, which starts at next-to-leading power (NLP). The...