Abstract
The move towards simplified models for Run II of the LHC will allow for stronger and more robust constraints on the dark sector. However there already exists a wealth of Run I data which should not be ignored in the run-up to Run II. Here we reinterpret public constraints on generic beyond-standard-model cross sections to place new constraints on a simplified model. We make use of an ATLAS search in the monojet + missing energy channel to constrain a representative simplified model with the dark matter coupling to an axial-vector Z′. We scan the entire parameter space of our chosen model to set the strongest current collider constraints on our model using the full 20.3 fb−1 ATLAS 8 TeV dataset and provide predictions for constraints that can be set with 20 fb−1 of 14 TeV data. Our technique can also be used for the interpretation of Run II data and provides a broad benchmark for comparing future constraints on simplified models.
Highlights
One solution is to rescale EFT constraints, by truncating the simulated signal such that only events for which the EFT approximation are valid are used to derive constraints [14, 22, 23]
Due to the sensitive dependence on the width it is worth stressing that since the model we assume here has no additional dark sector or standard model decays for the mediator, constraints set on dark matter mediators with dijet resonance searches in this part of parameter space can not be considered conservative: the width we use is the minimum width assuming equal coupling to each generation of quarks, and small changes to the dark sector can make a large difference to this width
As the LHC approaches Run II there is a clear move towards supplementing EFT analyses with simplified models, as a stronger and more robust way to constrain the dark sector
Summary
Our signal prediction is obtained by implementing the model in the FeynRules [46] and. We do note that based on the results in [53], we expect fixed-order NLO corrections to be modest after matching to a parton shower and applying the ATLAS monojet analysis cuts since the parton shower dilutes differences, helped by the loose cuts on additional jets. As such they should have a limited impact on our quantitative results and be negligible for qualitative results.
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