Search for contact interactions and large extra dimensions in the dilepton channel using proton-proton collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

TL;DR

This paper searches for signs of new physics such as contact interactions and large extra dimensions in dilepton events from proton-proton collisions at 8 TeV, finding no deviations and setting new lower limits on relevant energy scales.

Contribution

It provides the first limits on contact interaction scales and large extra dimension parameters using the 8 TeV ATLAS dilepton data.

Findings

No significant deviations from the Standard Model observed.

Lower limits on contact interaction scale $\\Lambda$ between 15.4 and 26.3 TeV.

Lower limits on string scale $M_{S}$ between 3.2 and 5.0 TeV.

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 $M_{S}$ between 3.2 TeV to 5.0 TeV.