Interpreting a CMS $lljjp_T^{\rm miss}$ Excess With the Golden Cascade of the MSSM

TL;DR

This paper interprets an excess observed by CMS as a specific supersymmetric decay chain involving squarks and neutralinos, fitting the data with a simplified MSSM model while considering constraints from other LHC searches.

Contribution

It provides a detailed MSSM-based explanation for the CMS excess using the golden cascade decay, and evaluates its viability against other experimental constraints.

Findings

The simplified MSSM model can fit the CMS excess and invariant mass edge.

Much of the parameter space remains allowed after ATLAS constraints.

Remaining parameter space is ruled out by two-lepton stop searches and jets plus missing energy searches.

Abstract

The CMS experiment recently reported an excess consistent with an invariant mass edge in opposite-sign same flavor (OSSF) leptons, when produced in conjunction with at least two jets and missing transverse momentum. We provide an interpretation of the edge in terms of (anti-)squark pair production followed by the `golden cascade' decay for one of the squarks: $\tilde q \rightarrow \tilde\chi_2^0 q \to \tilde l l q \to \tilde\chi_1^0 q l l$ in the minimal supersymmetric standard model (MSSM). A simplified model involving binos, winos, an on-shell slepton, and the first two generations of squarks fits the event rate and the invariant mass edge. We check consistency with a recent ATLAS search in a similar region, finding that much of the good-fit parameter space is still allowed at the 95% confidence level (CL). However, a combination of other LHC searches, notably two-lepton stop pair searches and jets plus $p_T^{\rm miss}$, rule out all of the remaining parameter space at the 95% CL.