Búsqueda de Dimensiones Espaciales Extras: Estudio del Estado Final de Dos Fotones en el Experimento ATLAS

The enormous difference between the Planck scale and the electroweak scale is known as the hierarchy problem. A prominent class of new physics models addresses the hierarchy problem through the existence of extra spatial dimensions. In this Thesis, data recorded in 2011 with the ATLAS detector at the Large Hadron Collider was used to perform a search for evidence of extra spatial dimensions through the analysis of the diphoton final state. The results were obtained using an integrated luminosity of 2.12 fb−1 of sqrt{s} = 7 TeV proton-proton collisions. The diphoton invariant mass (mgg) spectrum is observed to be in good agreement with the expected Standard Model background. In the large extra dimension scenario of Arkani-Hamed, Dimopoulos and Dvali, the results provide 95% CL lower limits on the effective Planck scale between 2.27 and 3.53 TeV, depending on the number of extra dimensions and the theoretical formalism used. The results also set 95% CL lower limits on the lightest Randall-Sundrum graviton mass of between 0.79 and 1.85 TeV, for values of the dimensionless coupling k/MPl varying from 0.01 to 0.1. Combining the results with the ones recently published by ATLAS using the dielectron and dimuon final states, the 95% CL lower limit on the Randall-Sundrum graviton mass for k/MPl= 0.01 (0.1) is 0.80 (1.95) TeV.