Search for chargino–neutralino pair production in final states with three leptons and missing transverse momentum in $$\sqrt{s} = 13$$ TeV pp collisions with the ATLAS detector

Abstract

A search for chargino–neutralino pair production in three-lepton final states with missing transverse momentum is presented. The study is based on a dataset of $$\sqrt{s} = 13$$ s = 13 TeV pp collisions recorded with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 $$\hbox {fb}^{-1}$$ fb - 1 . No significant excess relative to the Standard Model predictions is found in data. The results are interpreted in simplified models of supersymmetry, and statistically combined with results from a previous ATLAS search for compressed spectra in two-lepton final states. Various scenarios for the production and decay of charginos ($${\tilde{\chi }}^\pm _1$$ χ ~ 1 ± ) and neutralinos ($${\tilde{\chi }}^0_2$$ χ ~ 2 0 ) are considered. For pure higgsino $${\tilde{\chi }}^\pm _1{\tilde{\chi }}^0_2$$ χ ~ 1 ± χ ~ 2 0 pair-production scenarios, exclusion limits at 95% confidence level are set on $${\tilde{\chi }}^0_2$$ χ ~ 2 0 masses up to 210 GeV. Limits are also set for pure wino $${\tilde{\chi }}^\pm _1{\tilde{\chi }}^0_2$$ χ ~ 1 ± χ ~ 2 0 pair production, on $${\tilde{\chi }}^0_2$$ χ ~ 2 0 masses up to 640 GeV for decays via on-shell W and Z bosons, up to 300 GeV for decays via off-shell W and Z bosons, and up to 190 GeV for decays via W and Standard Model Higgs bosons.

Electroweak Phase Transition in the $Z_3$-invariant NMSSM Implications of LHC and Dark matter Searches and Prospects of Detecting the Gravitational Waves

“…On a conservative note, we do not consider possible situations which could result in weakened bounds on the masses of the electroweakinos when these have a compressed spectrum. In our case, for a light higgsino-triplet with a higgsino-like LSP, the lower bound on µ eff could go down to a value as small as ∼ 220 GeV, even with 139 fb −1 of data [125,126].…”

“…Together, these are expected to provide us with the most stringent lower bounds on the masses of the electroweakinos under diverse circumstances which are pointed out while discussing those. In addition, there are a few more rather recent LHC analyses [125,186,187] which are expected to be sensitive to the scenarios we study but yet not available in the public versions of either of these two packages. We will get back to these in section 4.3.2.…”

“…A CheckMATE analysis rules out BP-D1 (with r=1.12) via a CMS analysis [167] of 35.6 fb −1 worth data in the 3 + / E T final state where an opposite-sign, same-flavor (OS-SF) lepton (e or µ)-pair originates in the decay of an on-shell Z-boson coming from the decay of a heavier neutralino. Such a scenario, with µ eff as small as 275 GeV, would anyway be excluded more convincingly (i.e., with a larger r-value) by the recent LHC analyses in references [125,186] for the same final state which exploit 139 fb −1 of data.…”

EW SUSY production at the LHC

“…The first two searches discussed are the first SUSY searches with a fully-hadronic final state, at ATLAS [5] and CMS [6]. Following this an ATLAS search with a three-lepton final state is presented [7], and finally a four-𝑏-jet final state search from CMS [8].…”

“…The leptonic ATLAS search [7] considers the same 𝑊 𝑍 or 𝑊 𝑍 mediated decays as in Figure 1a, but with the bosons decaying leptonically. This search has two MSSM interpretations: firstly the same model as the CMS hadronic search, and secondly a Higgsino model, with the NLSP and LSP having very similar masses.…”