Measurement of diffractive photoproduction of dijets with ZEUS at HERA

Diffractive photoproduction of dijets was measured with the ZEUS detector 
at HERA using an integrated luminosity of 77.2 pb-1. The data cover a 
kinematic range of Q2 < 1 GeV2, 0.20 < y < 0.85 and x_pom < 0.025, 
where Q2 is the photon virtuality, y is the inelasticity and x_pom is 
the fraction of the proton momentum taken by the diffractive exchange. 
The two jets with the highest transverse energies, E_T^jet, were required 
to satisfy E_T^jet > 7.5 and 6.5 GeV, respectively, and to be in the 
pseudorapidity range -1.5 < eta^jet < 1.5. Differential cross sections 
are compared to perturbative QCD calculations using available
parameterisations of diffractive parton distributions of the proton.