Search for contact interactions and large extra dimensions in dilepton events from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

TL;DR

This paper reports a search for new physics phenomena like contact interactions and large extra dimensions in dilepton events from proton-proton collisions at 7 TeV, finding no deviations from the Standard Model and setting new lower bounds on relevant energy scales.

Contribution

It provides the first limits on contact interactions and large extra dimensions using dilepton events at 7 TeV with the ATLAS detector, improving previous constraints.

Findings

No significant deviations from the Standard Model observed.

Lower limits on contact interaction energy scale range from 9.0 to 13.9 TeV.

Lower limits on string scale in extra dimension models range from 2.4 to 3.9 TeV.

Abstract

A search for non-resonant new phenomena, originating from either contact interactions or large extra spatial dimensions, has been carried out using events with two isolated electrons or muons. These events, produced at the LHC in proton-proton collisions at sqrt(s) = 7 TeV, were recorded by the ATLAS detector. The data sample, collected throughout 2011, corresponds to an integrated luminosity of 4.9 and 5.0 fb-1 in the e+e- and mu+mu- channels, respectively. No significant deviations from the Standard Model expectation are observed. Using a Bayesian approach, 95% confidence limit lower limits ranging from 9.0 to 13.9 TeV are placed on the energy scale of llqq contact interactions in the left-left isoscalar model. Lower limits ranging from 2.4 to 3.9 TeV are also set on the string scale in large extra dimension models. After combination of these limits with results from a similar search in the diphoton channel, slightly more stringent limits are obtained.