Abstract
Hard processes in diffractive deep-inelastic scattering can be described by a factorisation into parton-level subprocesses and diffractive parton distributions. In this framework, cross sections for inclusive dijet production in diffractive deep-inelastic electron–proton scattering (DIS) are computed to next-to-next-to-leading order (NNLO) QCD accuracy and compared to a comprehensive selection of data. Predictions for the total cross sections, 40 single-differential and four double-differential distributions for six measurements at HERA by the H1 and ZEUS collaborations are calculated. In the studied kinematical range, the NNLO corrections are found to be sizeable and positive. The NNLO predictions typically exceed the data, while the kinematical shape of the data is described better at NNLO than at next-to-leading order (NLO). A significant reduction of the scale uncertainty is achieved in comparison to NLO predictions. Our results use the currently available NLO diffractive parton distributions, and the discrepancy in normalisation highlights the need for a consistent determination of these distributions at NNLO accuracy.
Highlights
Diffractive processes in deep-inelastic scattering, ep → eX Y, where the final state systems X and Y are separated in rapidity, have been studied extensively at the electron–Predictions for diffractive processes in deep-inelastic electron–proton scattering (DIS) can be obtained in the framework of perturbative QCD
According to the factorisation theorem for diffractive DIS (DDIS) [2], if the process is sufficiently hard, the calculation can be subdivided into two components: the hard partonic cross sections, dσn, are calculable within perturbative QCD (pQCD) in powers of αs(μR), which need to be convoluted with soft diffractive parton distribution functions (DPDFs, faD) that specify the contributing parton a inside the incoming hadron
We observe that the next-to-next-to-leading order (NNLO) cross sections are significantly higher than the data and are higher than nextto-leading order (NLO) calculations by about 20–40 % in the studied kinematical range
Summary
Diffractive processes in deep-inelastic scattering, ep → eX Y , where the final state systems X and Y are separated in rapidity, have been studied extensively at the electron–. Predictions for diffractive processes, and in particular for diffractive dijet production, were performed only in next-to-leading order QCD (NLO). These predictions were able to describe the measured cross sections satisfactorily, both in shape and normalisation We present the next-to-next-to-leading (NNLO) perturbative QCD calculations for dijet production in diffractive DIS. These calculations are performed for the first time and constitute the first NNLO predictions for a diffractive process. Different DPDF parameterisations are studied and we provide additional studies about the sensitivity of the dijet data for future DPDF determinations
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