Electroweak superpartners scrutinized at the LHC in events with multi-leptons

Iñaki Lara,Daniel E López-Fogliani,Carlos Muñoz

doi:10.1016/j.physletb.2019.01.010

Abstract

We analyze a multi-lepton signal plus missing transverse energy from neutrinos expected at the LHC for a bino-like neutralino as the lightest supersymmetric particle (LSP), when the left sneutrino is the next-to-LSP and hence a suitable source of binos. The discussion is carried out in the framework of the μνSSM, where the presence of R-parity violating (RPV) couplings involving right-handed neutrinos solves the μ problem and can reproduce simultaneously the neutrino data. Left sneutrinos/sleptons are pair-produced at pp collisions decaying to binos, with the latter decaying via RPV to Wℓ or Zν. This signal can be compared with LHC searches for electroweak superpartners through chargino–neutralino production. The reduced cross section of the sneutrino/slepton production in comparison with the one of the latter process, limits the sensitivity of the searches to small sneutrino/slepton masses. Although the resulting compressed spectrum typically evades the aforementioned searches, we show that analyses using recursive jigsaw reconstruction are sensitive to these scenarios. As a by-product, we find that the region of bino masses 110–120 GeV and sneutrino masses 120–140 GeV can give rise to a tri-lepton signal compatible with the local excess recently reported by ATLAS.

Highlights

Search for supersymmetry (SUSY) at accelerators has been focused mainly on signals with missing transverse energy (MET) inspired in R-parity conserving (RPC) models, such asThe only recent analyses [8, 9] of signals at the LHC for lightest supersymmetric particle (LSP) candidates in the μνSSM have been dedicated to the left sneutrino.1 There it was shown that because the left sneutrino has several relevant decay modes, the LEP lower bound on the sneutrino mass of about 90 GeV [14, 15, 16, 17, 18, 19] obtained under the assumption of branching ratios (BRs) one to leptons, via trilinear Rparity violating (RPV) couplings, is not applicable in the μνSSM
We will obtain regions of bino and sneutrino masses producing a tri-lepton signal compatible with the local excess reported by ATLAS [24]
Our analysis is implemented using the Madanalysis v5.17 [42, 43, 44] package, and validated with simulated Monte Carlo (MC) events corresponding to the production of neutralino-chargino pairs in the context of the minimal supersymmetric standard model (MSSM) decaying to a neutralino LSP and leptonically decaying gauge bosons, with selected masses of mχ±1 /χ02 = 200 and mχ01 = 100 GeV

Summary

Introduction

Search for supersymmetry (SUSY) at accelerators has been focused mainly on signals with missing transverse energy (MET) inspired in R-parity conserving (RPC) models, such as. This crucial task given the current experimental results on SUSY searches, has just started in the case of the μνSSM, and it has been concentrated for the moment on the electroweak sector as discussed above In this context, where basically the masses are poorly constrained or not at all, we consider crucial to take into account the recent searches at the LHC for events with multi-leptons plus MET [21, 22, 23, 24], since they can be compared with μνSSM signals. We will obtain regions of bino and sneutrino masses producing a tri-lepton signal compatible with the local excess reported by ATLAS [24] There, this signal was studied in the context of simplified RPC models, assuming wino-like chargino-neutralino production with a bino-like LSP.

The μνSSM

Bino-like LSP phenomenology in the μνSSM

Electroweak searches at the LHC

Results

Conclusions and outlook