Exploring Small Extra Dimensions at the Large Hadron Collider

Abstract

Many models that include small extra space dimensions predict graviton states which are well separated in mass, and which can be detected as resonances in collider experiments. It has been shown that the ATLAS detector at the Large Hadron Collider can identify such narrow states up to a mass of 2080 GeV in the decay mode G→e+e−, using a conservative model. This work extends the study of the e+e− channel over the full accessible parameter space, and shows that the reach could extend as high as 3.5 TeV. It then discusses ways in which the expected universal coupling of the resonance can be confirmed using other decay modes. In particular, the mode G→γγ is shown to be measurable with good precision, which would provide powerful confirmation of the graviton hypothesis. The decays G→μ+μ−, W+W −, Z0Z0 and jet-jet are measurable over a more limited range of couplings and masses. Using information from mass and cross-section measurements, the underlying parameters can be extracted. In one test model, the size of the extra dimension can be determined to a precision in length of 7 × 10−33 m.