Search for supersymmetric particles in events with lepton pairs and large missing transverse momentum in sqrt{s} = 7 TeV proton-proton collisions with the ATLAS experiment

Abstract

Results are presented of searches for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons in sqrt{s}=7 TeV proton-proton collisions at the Large Hadron Collider. Search strategies requiring lepton pairs with identical sign or opposite sign electric charges are described. In a data sample corresponding to an integrated luminosity of 35 pb-1 collected with the ATLAS detector, no significant excesses are observed. Based on specific benchmark models, limits are placed on the squark mass between 450 and 690 GeV for squarks approximately degenerate in mass with gluinos, depending on the supersymmetric mass hierarchy considered.

Figures (3)

• Figure 1: Distributions of $\MET$ for SS (upper) and OS (lower) lepton pair events passing the analysis selections. The data are shown as points with error bars superimposed on the expected SM background distributions determined (mostly data-driven) with MC simulation. The overflow point in the OS $\MET$ histogram is a likely candidate for cosmic ray interaction. In the bottom panel the ratio between data and the total SM background is shown. The histogram labelled "Standard Model" represents the sum of all backgrounds and the light (yellow) bands indicate the uncertainty on the MC predictions from finite MC statistics and uncertainties in cross section, luminosity and jet and lepton energy scales and resolutions. "SU4" represents a point in the mSUGRA/CMSSM parameter space with $m_0=200$ GeV, $m_{1/2}=160$ GeV, $A_0=-400$ GeV, $\tan\beta=10$ and $\mu >$0.
• Figure 2: Exclusion in the mSUGRA/CMSSM msugracmssm$(m_0,m_{1/2})$ plane for $\tan\beta=3$, $A_0=0$ and $\mu>0$, together with existing limits cdfsquarksgluinosd0squarksgluinosd0trileptonlepsusy. The expected (dashed line) and observed (full line) 95% C.L. exclusion limits are shown for the opposite sign (black line) and same-sign (blue line) analyses. The illustrated D0 limit assumes $\mu<0$.
• Figure 3: Expected and observed 95% C.L. exclusion limits in the $(m_{\tilde{g}},m_{\tilde{q}})$ plane for the specific MSSM models described in the text. The upper panel is for the SS analysis, the lower panel for the OS analysis.