The results of a search for supersymmetric particles in final states with four or more leptons (electrons or muons) and missing transverse momentum with the ATLAS detector are presented. The analysis uses a sample corresponding to an integrated luminosity of 2.06 fb−1 of proton-proton data recorded in 2011 at a centre-of-mass energy of 7 TeV. With an inclusive selection four events are observed, while 1.7±0.9 are expected from Standard Model processes. After applying a Z boson veto for leptons pairs with the same flavour and opposite charge, no events are observed for 0.7±0.8 events expected. Within the selection acceptance, we determine 95% C.L. visible cross-section upper limits for new phenomena of 3.5 fb and 1.5 fb for the selections without and with the Z-veto, respectively.
The combination of searches for squarks and gluinos in final states containing jets, missing transverse momentum and zero or one electron or muon is presented. In the MSUGRA/CMSSM framework with tan beta=3, A_0=0 and mu>0, squarks and gluinos of equal mass are excluded below 815 GeV. These are the most stringent limits to date.
This note describes an interpretation of a search for supersymmetry in final states with at least four isolated leptons (electrons or muons) and missing transverse momentum. The search used 2.06 fb$^{−1}$ of proton-proton collision data collected with the ATLAS experiment, and found no significant excess above expectations from Standard Model processes. Limits are shown for the Minimal Supergravity/Constrained Minimal Supersymmetric Standard Model (mSUGRA/CMSSM) with $m_0=A_0=0$, $\mu>0$ and one $R$-parity violating parameter $\lambda_{121}=0.032$ at the grand unification scale $m_{GUT}$. Keeping these parameters fixed, values of $m_{1/2}<800$ GeV are excluded at 95% CL if tan$\beta < 40$ and $m_{\tilde{\tau}_1}>80$ GeV. These are the first limits from the LHC experiments on a model with a $\tilde{\tau}_1$ as the lightest supersymmetric particle.