Abstract
High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the Z(nu {bar{nu }})+ jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by Z(ell ^+ell ^-)+ jet, W(ell nu )+ jet and gamma + jet production, and extrapolating to the Z(nu {bar{nu }})+ jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the-art calculations for all relevant V+ jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different V+ jet processes play a key role. The anticipated theoretical uncertainty in the Z(nu {bar{nu }})+ jet background is at the few percent level up to the TeV range.
Highlights
The signature of missing transverse energy (MET) is one of the most powerful tools in the interpretation of data from hadron colliders
We present a combination of state-of-the-art calculations for all relevant V + jets processes, including throughout next-tonext-to-leading order (NNLO) QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops
In the Standard Model (SM), MET arises from the neutrinos from the decay of W and Z bosons, and it can be used in their identification and study, as well as in the identification and study of Higgs bosons, top quarks and other SM particles whose decay products include W or Z bosons
Summary
The signature of missing transverse energy (MET) is one of the most powerful tools in the interpretation of data from hadron colliders. The determination of the background composition in signal and control regions, and the modeling of other key aspects of experimental analyses (e.g. lepton identification and reconstruction, missing energy, etc.) require a theoretical description of the various V + jets processes at the particle level This is provided by Monte Carlo (MC) samples based on multi-jet merging at LO or NLO QCD, and improvements based on higherorder theoretical calculations can be implemented through reweighting of MC events. For the fit of MC predictions to data, ATLAS and CMS analyses rely on the profile likelihood approach, where experimental and theoretical uncertainties are described in terms of nuisance parameters with Gaussian distributions In this context, the correlations of theoretical uncertainties across pT bins (shape uncertainties) and across different V + jets processes play a key role for searches at large MET. Technical plots on the individual sources of QCD and EW uncertainties are documented in Appendix B
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