  The role of transversity or helicity-flip generalized parton distributions
(GPDs) in leptoproduction of vector mesons is investigated within the framework
of the handbag approach. The transversity GPDs in combination with twist-3
meson wave functions, occur in the amplitudes for transitions from a
transversely polarized virtual photon to a longitudinal polarized vector meson.
The importance of the transversity GPDs can be examined in some of the spin
density matrix elements and in transverse target spin asymmetries. Using
suitable parametrizations of both helicity-flip and non-flip GPDs, which are
essentially taken from our previous papers, we estimate these observables and
compare the results with available data.
