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Combined collider constraints on neutralinos and charginos

Athron, Peter
Balázs, Csaba
Buckley, Andy
Cornell, Jonathan M.
Danninger, Matthias
Farmer, Ben
Fowlie, Andrew
Gonzalo, Tomás E.
Harz, Julia
Jackson, Paul
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Abstract
Searches for supersymmetric electroweakinos have entered a crucial phase, as the integrated luminosity of the Large Hadron Collider is now high enough to compensate for their weak production cross-sections. Working in a framework where the neutralinos and charginos are the only light sparticles in the Minimal Supersymmetric Standard Model, we use GAMBIT to perform a detailed likelihood analysis of the electroweakino sector. We focus on the impacts of recent ATLAS and CMS searches with of 13 TeV proton-proton collision data. We also include constraints from LEP and invisible decays of the Z and Higgs bosons. Under the background-only hypothesis, we show that current LHC searches do not robustly exclude any range of neutralino or chargino masses. However, a pattern of excesses in several LHC analyses points towards a possible signal, with neutralino masses of = (8–155, 103–260, 130–473, 219–502) GeV and chargino masses of = (104–259, 224–507) GeV at the 95% confidence level. The lightest neutralino is mostly bino, with a possible modest Higgsino or wino component. We find that this excess has a combined local significance of 3.3𝜎, subject to a number of cautions. If one includes LHC searches for charginos and neutralinos conducted with 8 TeV proton-proton collision data, the local significance is lowered to 2.9𝜎. We briefly consider the implications for dark matter, finding that the correct relic density can be obtained through the Higgs-funnel and Z-funnel mechanisms, even assuming that all other sparticles are decoupled. All samples, GAMBIT input files and best-fit models from this study are available on Zenodo.
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This work is licensed under a Creative Commons Attribution 4.0 International License.
Date
2019-05-08
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SpringerOpen
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GAMBIT Collaboration:., Athron, P., Balázs, C. et al. Combined collider constraints on neutralinos and charginos. Eur. Phys. J. C 79, 395 (2019). https://doi.org/10.1140/epjc/s10052-019-6837-x
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