  We investigate azimuthal correlations in deep inelastic diffractive
scattering, e + p -> e + \tilde{p} + X. The dependence of the ep cross section
on the angle between the lepton plane and some direction in the hadronic final
state can be written in a simple form; its measurement can be used to constrain
the cross section for longitudinally polarised photons. Using the model of
nonperturbative two-gluon exchange of Landshoff and Nachtmann we calculate the
distribution of the azimuthal jet angle in diffractive dijet production and
find that useful bounds on the longitudinal cross section for such events might
be obtained from its measurement. We then discuss the predictions of this model
for the dependence of the ep cross section on the azimuthal angle of the proton
remnant \tilde{p}, which contains information about the helicity content of the
pomeron.

High Energy Physics - Phenomenology