Gunar to Luciano et al.

1) our definition of the angle psi implies that a positive A_UT^sin\psi Fourier amplitude is equivalent to hadrons preferentially going to the right from the perspective of an incoming lepton facing a nucleon with spin up. This is the message of Eq. 2 in the current draft 89: A positive A_UT^sin\psi is a negative "left-right" asymmetry.

2) in pp collisions the reference direction is not the incoming unpolarized particle but the incoming *polarized* proton. That leads to the sign change mentioned in footnote 2: a hadron moving to the right as viewed from the perspective of the incoming unpolarized proton (or lepton) is moving to the left from the perspective of the incoming polarized proton.

If one wants to compare our lp->hX results with most of the pp->hX results then both sign changes have to be taken into account and a positive A_UT^sin\psi at HERMES corresponds to a positive A_N in the usual pp->hX reference frame. Or in other words, if sitting on the polarized proton, both at HERMES and at RHIC the pi+ tend to go to the left and the pi- go (more or less) to the right.