Consistent Excesses in the Search for $\tilde \chi_2^{\rm 0} \tilde \chi_1^{\rm \pm}$ : Wino/bino vs. Higgsino Dark Matter

Abstract

The quest for supersymmetric (SUSY) particles is among the main search channels currently pursued at the LHC. Particularly, electroweak (EW) particles with masses as low as a few hundred GeV are still viable. Recent searches for the ``golden channel'', $pp \to \tilde \chi_2^{\rm 0} \tilde \chi_1^{\rm \pm} \to \tilde \chi_1^{\rm 0} Z^{(*)} \, \tilde \chi_1^{\rm 0} W^{\pm (*)}$ show consistent excesses between ATLAS and CMS in the 2~lepton, 3-lepton and mono-jet searches, assuming $m_{\tilde \chi_2^{\rm 0}} \approx m_{\tilde \chi_1^{\rm \pm}} \gtrsim 200$ GeV and $\Delta m := m_{\tilde \chi_2^{\rm 0}} - m_{\tilde \chi_1^{\rm 0}} \approx 20$ GeV. This mass configuration arises naturally in SUSY scenarios with wino/bino Dark Matter (DM) or higgsino DM. In these scenarios the lightest supersymmetric particle (LSP), assumed to be the lightest neutralino, as a DM candidate, is in good agreement with the observed limits on the DM content of the universe, as well as with negative results from Direct Detection (DD) experiments. We analyze these two scenarios with respect to the observed excesses, taking into account all relevant experimental constraints. We show that in particular wino/bino DM with different signs of the $SU(2)$ and $U(1)$ soft SUSY-breaking parameters can describe well the experimental excesses, while being in agreement with all other constraints.