Consistent excesses in the LHC electroweak SUSY searches: GUT-based Singlino/Higgsino interpretation in the NMSSM

Abstract The search for signatures of supersymmetric models remains one of the main item on the BSM search program at the LHC, with EW SUSY partners still allowed with masses as low as a few hundred GeV. Over the last years, searches for the “golden channel”, $$pp \rightarrow \tilde{\chi }_{2}^0 \tilde{\chi }_{1}^\pm \rightarrow \tilde{\chi }_{1}^0 Z^{(*)} \, \tilde{\chi }_{1}^0 W^{\pm (*)}$$ p p → χ ~ 2 0 χ ~ 1 ± → χ ~ 1 0 Z ( ∗ ) χ ~ 1 0 W ± ( ∗ ) show consistent excesses between ATLAS and CMS in the 2 soft-lepton and 3 soft-lepton plus $$E_T\hspace{-4.5mm}/$$ E T / searches, assuming "Equation missing" and $$\Delta m_{21}{:=} m_{\tilde{\chi }_{2}^0} - m_{\tilde{\chi }_{1}^0} \approx 20 \,\, \textrm{GeV}$$ Δ m 21 : = m χ ~ 2 0 - m χ ~ 1 0 ≈ 20 GeV . We interpret these excesses in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We assume a singlino dominated lightest neutralino, $$\tilde{\chi }_{1}^0$$ χ ~ 1 0 , as a Dark Matter (DM) candidate. The second and third lightest neutralinos, $$\tilde{\chi }_{2,3}^0$$ χ ~ 2 , 3 0 are higgsino like, with the higgsino mixing parameter $$\mu $$ μ being smaller than the soft SUSY-breaking bino and wino masses, $$M_1$$