Abstract

This work presents a new inclusive search for supersymmetry (SUSY) by the ATLAS experiment at the LHC in proton-proton collisions at a center-of-mass energy sqrt(s) = 7 TeV in final states with jets, missing transverse momentum and one or more isolated electrons and/or muons. The search is based on data from the full 2011 data-taking period, corresponding to an integrated luminosity of 4.7 inverse fb. Single- and multi-lepton channels are treated together in one analysis. An increase in sensitivity is obtained by simultaneously fitting the number of events in statistically independent signal regions, and the shapes of distributions within those regions. A dedicated signal region is introduced to be sensitive to decay cascades of SUSY particles with small mass differences ("compressed SUSY"). Background uncertainties are constrained by fitting to the jet multiplicity distribution in background control regions. Observations are consistent with Standard Model expectations, and limits are set or extended on a number of SUSY models.

Highlights

  • Supersymmetry (SUSY) [1,2,3,4,5,6,7,8,9] is a candidate for physics beyond the Standard Model (SM)

  • This paper presents a new inclusive search with the ATLAS detector for SUSY in final states containing jets, one or more isolated leptons and EmT iss

  • This analysis is based on three broad classes of event selection: (i) a hard single-lepton channel that is an extension to higher masses of the previous search [16], (ii) a soft single-lepton channel geared towards SUSY models with small mass differences in the decay cascade, and (iii) a multilepton channel aimed at decay chains with higher lepton multiplicities

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Summary

INTRODUCTION

Supersymmetry (SUSY) [1,2,3,4,5,6,7,8,9] is a candidate for physics beyond the Standard Model (SM). In the minimal supersymmetric extension of the Standard Model (MSSM) [11,12,13,14,15] such particles decay into jets, leptons and the lightest supersymmetric particle (LSP). This paper presents a new inclusive search with the ATLAS detector for SUSY in final states containing jets, one or more isolated leptons (electrons or muons) and EmT iss. Previous searches in these channels have been conducted by both the ATLAS [16,17,18] and CMS [19,20,21,22] collaborations. Background uncertainties are constrained by fitting to the jet-multiplicity distribution in background control regions

THE ATLAS DETECTOR
SUSY SIGNAL MODELING AND SIMULATED EVENT SAMPLES
OBJECT RECONSTRUCTION
Object preselection
Signal object selection
TRIGGER AND DATA COLLECTION
EVENT SELECTION
BACKGROUND
Reweighting of W þ jets and Z þ jets simulated samples
Multijet background
Other backgrounds
VIII. SYSTEMATIC UNCERTAINTIES
Background fit validation
RESULTS AND INTERPRETATION
CONCLUSION
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