Search for Large Extra Dimensions in Dimuon Events with the CMS Experiment at $\sqrt{s}$ = 8 TeV

The Large Hadron Collider (LHC) experiment operated at a center of mass energy of √ s = 8 TeV during the 2012 Run and the Compact Muon Solenoid (CMS) experiment recorded signatures of particle collisions with an integrated luminosity of 20.6 fb−1. Sig- natures from collisions where two high energy muons emerge are studied and interpreted in the Arkani-Hamed, Dimopoulos, Dvali (ADD) model of large spartial extra dimensions. The ADD model predicts a non-resonant excess in the tails of the dimuon invariant mass distribution. Several background processes are studied with Monte Carlo simulation. The Drell-Yan process is the dominant source of background events and it is studied in detail up to NNLO in QCD and NLO in EW. Several sources of systematic uncertainty influence both the theoretical model and the measurement and are studied in detail for high mass dimuon events. The dimuon spectrum with yet inaccessible particle energies is evaluated and no ev- idence for a signal is observed. The number of events above dimuon masses ofunit[1.9]TeV is used to set lower limits on the string scale Ms between 4.6 TeV and 3.1 TeV for n = 3 to n = 7 extra dimensions in the ADD model at 95% confidence level. The exclusion limits are further extended by a combination of dilepton mass spectra (ee+µµ) for masses above 2.0 TeV. The combination gives lower limits on Ms between 4.9 TeV and 3.3 TeV for n = 3 to n = 7 extra dimensions.