We investigate the infrared singularity structure of Feynman diagrams entering the next-to-leading-order (NLO) DGLAP kernel (nonsinglet). We examine cancellations between diagrams for two gluon emission contributing to NLO kernels. We observe the crucial role of color coherence effects in cancellations of infra-red singularities. Numerical calculations are explained using analytical formulas fo...

Heading towards a full automation of next-to-leading order (NLO) QCD corrections, one important ingredient is the analytical integration over the one-particle phase space of the unresolved particle that is necessary when adding the subtraction terms to the virtual corrections. We present the implementation of these integrated dipoles in the MadGraph framework. The result is a package that allow...

We present an extension of the antenna subtraction formalism at NLO to include massive final state fermions. The basic ingredients to the subtraction terms, the NLO massive final-final antenna functions are derived and integrated over the corresponding factorised phase space. Those antenna functions account for all soft, collinear and quasi-collinear limits of the QCD matrix elements involving ...

The measurement and QCD analysis of neutral and charged current cross sections at HERA are presented. For the kinematic range of four-momentum transfer Q 2 between ≈ 1 GeV 2 and 30000 GeV 2 and Bjorken x between 0.0013 and 0.65 the data are compared to NLO QCD predictions. In dedicated NLO QCD analyses the extraction of the parton distribution functions of the proton is performed. Results for t...

The measurement and QCD analysis of neutral and charged current cross sections at HERA are presented. For the kinematic range of four-momentum transfer Q 2 between ≈ 1 GeV 2 and 30000 GeV 2 and Bjorken x between 0.0013 and 0.65 the data are compared to NLO QCD predictions. In dedicated NLO QCD analyses the extraction of the parton distribution functions of the proton is performed. Results for t...

Most of the experiments performed during this course are perfectly described by the principles of linear optics. This assumes that interacting optical beams (i.e. beams crossing paths) will not affect each other. As the light intensity is increased, however, this assumption no longer holds; we are forced to consider the possibility of nonlinear interactions. Nonlinear optical effects manifest i...

We discuss W boson production at HERA including NLO QCD corrections. A detailed comparison with previous work is presented.

In recent years, there has been extensive research and continuous development on second-order nonlinear optical (NLO) crystal materials due to their potential applications in telecommunications, THz imaging and spectroscopy, optical information processing, and optical data storage. Recent progress in second-order NLO ionic organic crystal materials is reviewed in this article. Research has show...

We carry out next-to-leading order (NLO) parton model calculations for the standard hard “QCD” processes in the massless Schwinger model. The asymptotic expansion of the exact result for the deep inelastic cross section is used to infer the NLO distribution function. These distribution functions are then used to calculate the NLO Drell-Yan parton model cross section and it is found to agree wit...

We have computed the cross section for tt̄ production by gluon-gluon fusion at next-toleading order (NLO) in the QCD coupling, keeping the full dependence on the tt̄ spins. Furthermore we have determined to the same order the spin dependent cross sections for the processes g+q(q̄)→ tt̄+q(q̄). Together with our previous results [1] for q+ q̄→ tt̄(g) these results allow for predictions, at NLO QCD, of t...