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

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 full LHC 2012 proton-proton collision dataset recorded by the ATLAS detector is used, corresponding to 20~fb$^{-1}$ at $\sqrt{s}$ = 8 TeV. In addition to the dilepton invariant mass spectrum as a discriminating variable, the contact interaction search utilizes forward-backward asymmetry. No significant deviations from the Standard Model expectation are observed. Lower limits are set on the new physics parameters of interest at the 95% credibility level. For $\ell\ell q q$ contact interactions, limits are set on the contact interaction scale $\Lambda$ between 15.6 TeV and 26.3 TeV. Limits are also set on the string scale $M_{\rm S}$ for large extra spatial dimensions, from 4.1 TeV to 6.1 TeV.