Search for dilepton resonances in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

Abstract

This Letter reports on a search for narrow high-mass resonances decaying into dilepton final states. The data were recorded by the ATLAS experiment in pp collisions at sqrt(s) = 7 TeV at the LHC and correspond to a total integrated luminosity of 1.08/fb (1.21/fb) in the ee (mumu) channel. No statistically significant excess above the Standard Model expectation is observed and upper limits are set at the 95% C.L. on the cross section times branching ratio of Z' resonances and Randall-Sundrum gravitons decaying into dileptons as a function of the resonance mass. A lower mass limit of 1.83 TeV on the Sequential Standard Model Z' boson is set. A Randall-Sundrum graviton with coupling k/M_Pl=0.1 is excluded at 95% C.L. for masses below 1.63 TeV.

Figures (2)

• Figure 1: Dielectron (top) and dimuon (bottom) invariant mass ($m_{\ell\ell}$) distribution after final selection, compared to the stacked sum of all expected backgrounds, with three example $Z'_{\rm SSM}$ signals overlaid. The bin width is constant in $\log m_{\ell\ell}$.
• Figure 2: Expected and observed 95% C.L. upper limits on $\sigma B$ as a function of mass for $Z'$ (top) and $G^*$ (bottom) models. Both results show the combination of the electron and muon channels. The thickness of the $Z'_{\rm SSM}$ (top) and the $G^*$ for $k/\overline{M}_{Pl}$=0.1 (bottom) theory curves illustrate the theoretical uncertainties.