Measuring the Pion substructure with Radiative Positronic Pion Decays

This dissertation presents an analysis of the PEN data from 2008 searching for the rare decay π + → e + νγ. The region of phase space was E γ > 10MeV and an opening angle of θ eγ > 40 ◦ . The goal was to measure the form factors of the pion, F A and F V . From an observation of 3,884 events we evaluated values of F A = 0.0193 ± 0.008 and F V = 0.0191 ± 0.008. For historical comparison the value of γ ≡ F A /F V was also calculated assuming the Conserved Vector Current hypothesis from the standard model. That produced a result of γ = 0.459±0.057. Both of these results agree with the world experimental average and the standard model within 1σ. The analysis procedure is described in this dissertation along with an in depth treatment of the simulation software produced for the determination of the system acceptance.

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