Dark matter interpretations of ATLAS searches for the electroweak production of supersymmetric particles in $\sqrt{s} = 8$ TeV proton-proton collisions

TL;DR

This paper evaluates how ATLAS searches at 8 TeV constrain dark matter candidates within supersymmetric models, especially focusing on the lightest neutralino mass and the impact of various experimental data.

Contribution

It performs a likelihood-driven scan of a five-dimensional SUSY model incorporating multiple experimental constraints to assess the impact of ATLAS searches on dark matter parameter space.

Findings

86% of models with neutralino mass less than 65 GeV are excluded by ATLAS searches.

Limited impact on models with heavier neutralinos or compressed spectra.

ATLAS searches significantly constrain models with light neutralinos below 65 GeV.

Abstract

A selection of searches by the ATLAS experiment at the LHC for the electroweak production of SUSY particles are used to study their impact on the constraints on dark matter candidates. The searches use $20\,{\rm fb}^{-1}$ of proton-proton collision data at $\sqrt{s}=8$ TeV. A likelihood-driven scan of a five-dimensional effective model focusing on the gaugino--higgsino and Higgs sector of the phenomenological minimal supersymmetric Standard Model is performed. This scan uses data from direct dark matter detection experiments, the relic dark matter density and precision flavour physics results. Further constraints from the ATLAS Higgs mass measurement and SUSY searches at LEP are also applied. A subset of models selected from this scan are used to assess the impact of the selected ATLAS searches in this five-dimensional parameter space. These ATLAS searches substantially impact those models for which the mass $m(\tilde{\chi}^0_1)$ of the lightest neutralino is less than 65 GeV, excluding 86% of such models. The searches have limited impact on models with larger $m(\tilde{\chi}^0_1)$ due to either heavy electroweakinos or compressed mass spectra where the mass splittings between the produced particles and the lightest supersymmetric particle is small.