The hallmark way to search for electroweakinos in natural supersymmetry at the LHC involves the trilepton plus missing energy (${\cancel{E}}_T$) final state. This approach assumes an electroweakino mass hierarchy that allows for cascade decays leading to a final state of $W^{\pm }{Z}^0$ plus ${\cancel{E}}_T$. There are, however, situations when that decay pattern may not exist, such as when a chargino is the lightest electroweakino and the lightest supersymmetric particle is the gravitino. In regions of the parameter space where this ordering occurs, the production of any combination of neutralino/chargino leads to a $W^{+}{W}^{-}+{\cancel{E}}_T+X$ final state, where $X$ could be additional jets or leptons. If $X$ is soft, then all neutralino/chargino production modes fall into the same experimental final state, ${\ell }^{+}{\ell }^{-}+{\cancel{E}}_T$. ATLAS and CMS have $W^{+}({\ell }^{+}\nu )W^{-}({\ell }^{-}\overline{\nu })+{\cancel{E}}_T$ searches, but their interpretation assumes a spectrum consisting of an isolated charged state. In this paper, we identify the circumstances under which natural supersymmetry models can avoid $W^{\pm }{Z}^0+{\cancel{E}}_T$ bounds. For scenarios that escape $W^{\pm }{Z}^0+{\cancel{E}}_T$, we then recast the latest ATLAS $W^{+}{W}^{-}+{\cancel{E}}_T$ search, taking into account all the states that contribute to the same signal. Assuming the lightest supersymmetric particle is massless, we find a bound of 460 GeV for a Higgsino-like degenerate doublet. Finally, we extend our arguments to a nonsupersymmetric simplified model containing new electroweak-scale $SU(2{)}_w$ doublets and singlets.

• Received 18 December 2019
• Accepted 27 January 2020

DOI:https://doi.org/10.1103/PhysRevD.101.035014

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society