Search for Large Extra Dimension in Dielectron Final State at the LHC

In the framework of the Standard Model, the Higgs boson mass is not stable against the higher order corrections. The point that the Higgs boson mass is not of the order of Planck scale or GUT scale but rather of the order of 100 GeV is usually referred to as the hierarchy problem.

One way to solve this problem was proposed by Arkani-Hamed, Dimipolous, and Dvali (ADD) in 1998. In the ADD framework, the SM particles are confined to four-dimensional space–time and gravity is free to propagate into all 4 + nED dimensions, where nED is the number of extra dimensions. In particle collisions at the LHC or Tevatron, the cross sections in the large extra dimensions model usually consist of the SM contributions, the interference between the SM and extra dimensions diagrams, and the pure extra dimensions contributions.

In this work we performed a search for the effects of large extra dimensions through virtual graviton exchange at the LHC resulting in dielectron final states using 20/fb of data collected by the CMS detector at the centre-of-mass energy of 8 TeV in 2012. We concentrated on the dielectron invariant mass to look for the large extra dimensions. In the following we presented the dielectron invariant mass spectrum compared with the SM predictions and a simulated ADD signal with a specific set of ADD parameters. The error bars reflect the statistical uncertainty.

Since data has been found to be in a good agreement with the Standard Model predictions, we set limits on the parameters of the ADD model, namely the reduced Planck scale for various number of extra

dimensions. The results are presented in the following table with and without including next to leading order effects on signal.

More details of the results can be found in:

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsEXO12031