[PEPPo] Proposal

[hyde at jlab.org]

One quick comment on the DVCS/GPD
section of the proposal.
The GPDs H, H-tilde, E, E-tilde are twist 2.
The Transversity GPDs are twist-3.
To the extent that the transversity GPDs appear in
cos(2phi) or cos(3phi) observables, they are lowest
twist in those observables, but I think it is slightly
erroneous to describe e.g. H and H_T as both
"lowest twist"

Also, H, H-tilde, E, E-tilde, are quark helicity conserving,
but E, E-tilde are nucleon helicity flip.
So make sure you keep the words "quark helicity"
and don't just say "helicity"

Charles Hyde