Abstract
A search is presented for the pair production of light scalar top quarks in sqrt(s) = 7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. This analysis uses the full data sample collected during 2011 that corresponds to a total integrated luminosity of 4.7 fb-1. Light scalar top quarks are searched for in events with two opposite-sign leptons (e, mu), large missing transverse momentum and at least one jet in the final state. No excess over Standard Model expectations is found, and the results are interpreted under the assumption that the light scalar top decays to a b-quark in addition to an on-shell chargino whose decay occurs through a virtual W boson. If the chargino mass is 106 GeV, light scalar top quark masses up to 130 GeV are excluded for neutralino masses below 70 GeV.
Highlights
In this presented iLne√ttesr,=a search for direct stop pair production is 7 TeV proton–proton collisions recorded with the ATLAS detector at the Large Hadron Collider, considering a SUSY particle mass hierarchy such that mt > mt1 > and the t1 decays exclusively via b + χ1±
The largest source of systematic uncertainty on the ttbackground evaluation is the uncertainty on the jet energy scale (JES), with smaller contributions coming from the jet energy resolution (JER) uncertainty [45], the theory and Monte Carlo (MC) modelling uncertainties, the systematic uncertainties on the b-tagging efficiency [48], and the uncertainty arising from the limited numbers of MC and data events
Good agreement is observed across all channels, and the absence of evidence for light scalar top production allows a limit to be set on the visible cross section for non-Standard Model (SM) physics, σvis = σ × × A, for which this analysis has an efficiency and acceptance A
Summary
In this presented iLne√ttesr,=a search for direct stop pair production is 7 TeV proton–proton collisions recorded with the ATLAS detector at the Large Hadron Collider, considering a SUSY particle mass hierarchy such that mt > mt1 > (mχ1± + mb) and the t1 decays exclusively via b + χ1±. 160 GeV would be produced with relatively large cross sections—between 245 pb and 41 pb In this search, dilepton final states ( = e, μ) are considered. Dilepton final states ( = e, μ) are considered These events could contribute to an anomaly in the measured ttcross section, the relative contribution would be small due to the low transverse momenta of the visible decay products. By targeting very light top squarks, this analysis is complementary to other direct stop searches recently presented by the ATLAS experiment [17, 18]
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