https://doi.org/10.1140/epjc/s10052-019-6837-x
Regular Article - Experimental Physics
Combined collider constraints on neutralinos and charginos
1
School of Physics and Astronomy, Monash University, Melbourne, VIC, 3800, Australia
2
Australian Research Council Centre of Excellence for Particle Physics at the Tera-Scale, Melbourne, Australia
3
School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
4
Department of Physics, McGill University, 3600 rue University, Montréal, QC, H3A 2T8, Canada
5
Department of Physics, University of British Columbia, Vancouver, BC, Canada
6
Department of Physics, Imperial College London, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK
7
Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing, 210023, Jiangsu, China
8
Department of Physics, University of Oslo, 0316, Oslo, Norway
9
LPTHE-CNRS-UPMC, Boîte 126, T13-14 4e étage, 4 Place Jussieu, 75252, Paris CEDEX 05, France
10
Department of Physics, University of Adelaide, Adelaide, SA, 5005, Australia
11
Physics and Astronomy Department, University of California, Los Angeles, CA, 90095, USA
12
Department of Physics and Astronomy, University of Kansas, Malott Hall, Lawrence, KS, 66045, USA
* e-mail: martin.white@adelaide.edu.au
Received:
4
October
2018
Accepted:
3
April
2019
Published online:
8
May
2019
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 [see pdf] 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 [see pdf] = (8–155, 103–260, 130–473, 219–502) GeV and chargino masses of [see pdf] = (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 
, 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 2.9
. 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.
© The Author(s), 2019
