Abstract
A recent CMS analysis has reported the observation of an excess in the invariant mass distribution of the opposite-sign same-flavour lepton pair, which can be interpreted as a kinematic edge due to new physics. Using collider simulation tools, we recast relevant LHC search results reported by ATLAS and CMS collaborations in order to determine constraints on supersymmetric models that could produce the observed features. In particular, we focus on models involving cascade decays of light-flavour squarks and sbottoms. We find no favourable supersymmetry scenario within our exploration that could explain the origin of the excess when other LHC constraints are taken into account.
Highlights
In this work we perform a detailed study on the possibility of explaining the dilepton excess with several SUSY models taking into account a comprehensive list of LHC constraints from a number of ATLAS and CMS direct SUSY searches
It is known that the OSSF dilepton pair in the decay of the second lightest neutralino χ02 via on-shell slepton and off-shell Z exhibit an edge-like shape at medge = mχ02
As a result we find a good fit to the dilepton excess at ∆m = 130 GeV and mb1 ∈ [350, 400] GeV, this region is already in tension with the SL5j signal region in the ATLAS jets plus 1–2 lepton analysis
Summary
CMS reported an excess of events in the dilepton plus missing energy channel [1, 2] in the 8 TeV, 19.4 fb−1 data. The analysis requires an OSSF lepton pair with pT > 20 GeV. It requires ≥ 2 jets with pT > 40 GeV and E/ T > 150 GeV or ≥ 3 jets with pT > 40 GeV and E/ T > 100 GeV. The excess is observed in the central region where both leptons satisfy |ηlep| < 1.4. It exhibits an edge in the dilepton invariant mass distribution around m = 78 GeV. The counting experiment in the m ∈ [20, 70] GeV region shows an excess of ∼ 130 events over the Standard Model expectation, which corresponds to a standard deviation of 2.6 σ
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