Abstract
Extending previous work on the predictions for the production of supersymmetric (SUSY) particles at the LHC, we present the fully differential calculation of the next-to-leading order (NLO) SUSY-QCD corrections to the production of squark and squark–antisquark pairs of the first two generations. The NLO cross sections are combined with the subsequent decay of the final state (anti)squarks into the lightest neutralino and (anti)quark at NLO SUSY-QCD. No assumptions on the squark masses are made, and the various subchannels are taken into account independently. In order to obtain realistic predictions for differential distributions the fixed-order calculations have to be combined with parton showers. Making use of the Powheg method we have implemented our results in the Powheg-Box framework and interfaced the NLO calculation with the parton shower Monte Carlo programs Pythia6 and Herwig++. The code is publicly available and can be downloaded from the Powheg-Box webpage. The impact of the NLO corrections on the differential distributions is studied and parton shower effects are investigated for different benchmark scenarios.
Highlights
Though results for the individual subchannels can be obtained, they are provided in the approximation of scaling the exact LO cross section of the individual subchannel with a global K -factor, that is given by the ratio of the total next-to-leading order (NLO) cross section and the total LO cross section for degenerate squark masses
In the second part we present some results for the combination of production and decay, both for squark–antisquark and squark pair production
This part extends our previous results for the squark pair production processes in [54] by including the NLO corrections to the decay
Summary
In [54,55,56], we have calculated the NLO corrections to the pair production of squarks of the first two generations and implemented the cross section in a fully flexible partonic Monte Carlo program without making any simplifying assumptions on the squark masses and treating the different subchannels individually. In order to improve the accuracy of the cross section predictions a proper NLO treatment of the individual subchannels is necessary, without relying on an averaged K -factor It was found, that while the shapes of semi-inclusive distributions are only mildly affected by NLO corrections, this is not the case for more exclusive observables. In order to obtain realistic predictions for exclusive observables we have combined our fixed-order NLO calculations with parton showers To this end, the processes have been implemented in the Powheg-Box framework [56,59] and interfaced with different parton shower programs.
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