Combined collider constraints on neutralinos and charginos

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2019

Authors

Athron, P.
Balázs, C.
Buckley, A.
Cornell, J.M.
Danninger, M.
Farmer, B.
Fowlie, A.
Gonzalo, T.E.
Harz, J.
Jackson, P.

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European Physical Journal C: Particles and Fields, 2019; 79(5):395-1-395-52

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Peter Athron, Csaba Balázs, Andy Buckley, Jonathan M. Cornell, Matthias Danninger ... Abhishek Sharma ... et al. (GAMBIT Collaboration)

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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 Open image in new window 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 Open image in new window = (8–155, 103–260, 130–473, 219–502) GeV and chargino masses of Open image in new window = (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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© The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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