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

TL;DR

This paper investigates multi-lepton signals from electroweak superpartners in the mbdaSSM at the LHC, highlighting the potential to detect sneutrino and Bino masses and explaining recent ATLAS excesses.

Contribution

It introduces a novel analysis of sneutrino and Bino production in the mbdaSSM, demonstrating sensitivity of recursive jigsaw reconstruction to compressed spectra and explaining ATLAS excesses.

Findings

Sneutrino and Bino masses around 110-140 GeV can produce detectable signals.

Recursive jigsaw reconstruction enhances sensitivity to compressed spectra.

Possible explanation for ATLAS observed tri-lepton excess.

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 $\mu \nu$SSM, where the presence of $R$-parity violating (RPV) couplings involving right-handed neutrinos solves the $\mu$ 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 $W\ell$ or $Z\nu$. 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.