Bose-Einstein correlations in 7 TeV proton-proton collisions in the ATLAS experiment

In this thesis, Bose-Einstein correlations (BEC) of like-sign charged boson pairs (mainly π^±) collected by the ATLAS experiment at the Large Hadron Collider (LHC) in 7 TeV proton-proton collisions are analyzed in terms of various parametrizations: the wave function approach, the quantum optical approach and the τ model. The effect of BEC is experimentally measured as a relative enhancement of the production of identical bosons with small 4-momentum differences, Q = √(-(k₁ - k₂)²), compared to the case without BEC. In order to see this enhancement, one constructs the correlation function C₂(Q), which is the ratio of the two-particle probability density to the product of the single-particle densities assuming Gaussian, Cauchy-Lorentzian or Levy source emission probabilities. (author)