Single spin asymmetry in $e+p\to e'+B^\uparrow+X$

We study an exotic type of single spin asymmetry in unpolarized electron-proton scattering, in which the outgoing electron momentum exhibits a left-right asymmetry relative to the transverse spin of the leading baryon $B$ in the target fragmentation region. We lay out two theoretical frameworks for describing this effect: The twist-three fracture function at high-$Q^2$ and the spin-dependent odderon in the high energy limit.