Eur. Phys. J. C 19, 485-492
Generalized parton distributions with helicity flipM. Diehl
Deutsches Elektronen-Synchroton DESY, 22603 Hamburg, Germany
(Received: 7 February 2001 / Published online: 23 March 2001 -© Springer-Verlag 2001)
We show that for both quarks and gluons there are eight generalized parton distributions in the proton: four which conserve parton helicity and four which do not. We explain why time reversal invariance does not reduce this number from eight to six, as previously assumed in the literature.
© Società Italiana di Fisica, Springer-Verlag 2001