Abstract

A search is conducted for non-resonant new phenomena in dielectron and dimuon final states, originating from either contact interactions or large extra spatial dimensions. The LHC 2012 proton–proton collision dataset recorded by the ATLAS detector is used, corresponding to 20 fb^{-1} at sqrt{s} = 8 TeV. The dilepton invariant mass spectrum is a discriminating variable in both searches, with the contact interaction search additionally utilizing the dilepton forward-backward asymmetry. No significant deviations from the Standard Model expectation are observed. Lower limits are set on the ell ell q q contact interaction scale Lambda between 15.4 TeV and 26.3 TeV, at the 95 % credibility level. For large extra spatial dimensions, lower limits are set on the string scale M_mathrm{S} between 3.2 TeV to 5.0 TeV.

Highlights

  • Many theories beyond the Standard Model (SM) predict new phenomena which give rise to dilepton final states, such as new resonances

  • A complementary search is performed for new phenomena that appear as broad deviations from the SM in the dilepton invariant mass distribution or in the angular distribution of the leptons

  • To study the track curvature source, various investigations were carried out wherein additional charge misidentification is injected into the simulation to ascertain its effect, and the Inner Detector (ID) track resolution in q/ p is varied to assess the probability of a change of charge sign

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Summary

Introduction

Many theories beyond the Standard Model (SM) predict new phenomena which give rise to dilepton final states, such as new resonances. These have been searched for using the ATLAS detector at the Large Hadron Collider (LHC) and are reported elsewhere [1]. A complementary search is performed for new phenomena that appear as broad deviations from the SM in the dilepton invariant mass distribution or in the angular distribution of the leptons (where the leptons considered in this analysis are electrons or muons). The phenomena under investigation are contact interactions (CI) and large extra dimensions (LED)

Theoretical motivation
Data and Monte Carlo samples
Event selection and background estimation
Event yields
Systematic uncertainties
Background
Statistical interpretation
Results
10 Conclusions
Full Text
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