Cross sections for inclusive dijet production in diffractive deep-inelastic scattering are calculated for the first time in next-to-next-to-leading order (NNLO) accuracy.
These cross sections are compared to several HERA measurements published by the H1 and ZEUS collaborations.
We computed the total cross sections, 49 single-differential and five double-differential distributions for six HERA measurements.
The NNLO corrections are found to be large and positive.
The normalization of the resulting predictions typically exceeds the data, while the kinematical shape of the data is described better at NNLO than at next-to-leading order (NLO).
Our results use the currently available NLO diffractive parton distributions, and the discrepancy in normalization highlights the need for a consistent determination of these distributions at NNLO accuracy.