Search for contact interactions using the dimuon mass spectrum in P-P collisitons at $\sqrt s$ = 8 TeV at CMS

The mass hierarchy problem associated with the standard model suggests that there might be more fundamental particles in nature. If quarks and leptons have sub- structures, known as preons, the manifestation of compositeness can be a four-fermion contact interaction. The experimental signal for contact interactions is a non-resonant enhancement of the number of events in the high-mass region of the dimuon mass spec- trum. This dissertation describes a detailed search strategy for contact interactions using the Compact Muon Solenoid experiment. The dimuon mass spectrum above 300 GeV has been studied using the data collected in 2012 at √s = 8 TeV corresponding to an in- tegrated luminosity of 20.6 fb−1. Comparison of the observed mass spectrum with a fully simulated Monte Carlo prediction for the standard model shows no significant deviation. In the context of the left-left isoscalar model for contact interactions with compositeness energy scale Λ, exclusion lower limits are placed on Λ of 14.8 TeV and 12.4 TeV at a 95 % confidence level for constructive and destructive interference, respectively. The limits obtained from the study represent the most stringent limits to date.