Producción de J/$\psi\to e^+e^-$ en ATLAS a $\sqrt{s}$=7 TeV. Determinación de la eficiencia del Trigger de e y $\gamma$ con 45pb$^{−1}$ de datos para la búsqueda del Higgs en el canal H$\to\gamma\gamma$

The present thesis summarizes the observation of J/$\psi$ with the ATLAS detector in the two electron decay channel, the measurement of the efficiency of the electron and photon triggers using ATLAS data and the expected efficiency of the photon trigger on the Higgs search in the two photon decay channel. The studies on this thesis focus on the performance of the e/$\gamma$ trigger system, with special emphasis on the impact in the search of the Higgs boson in the di-photon decay channel. 45 pb$^{-1}$ of data collected by ATLAS at $\sqrt{s}$=7 TeV in 2010 is used for this analysis. A data-driven method called "Tag and Probe" is used to get the efficiency of the electron trigger from the J/$\psi$ decay on ATLAS data. A method to subtract the background is developed for this thesis to deal with the low statistics of the data sample. A "pseudo-Tag and probe" is implemented to extract from data the photon trigger efficiency relative to the selection of a Higgs dacaying in two photons.