Implementation of K-matrix formalism in the D0 -> K_s pi+ pi- amplitude model

This report presents the work of a summer student project aimed at the implementation of a model for the decay amplitude of $D^0 \rightarrow K_S \pi^+ \pi^-$ in the context of investigating mixing and CP violation in the charm sector. The analysis of this decay gives direct axis to the mixing parameters $x$ and $y$ which can be measured by fitting the model constructed to data. Decay dynamics are understood in terms of resonances, which can as a first aproximation be parametrised by Breit-Wigner curves, failing however to always respect unitarity. To avoid this problem the so-called K-matrix formalism with Production vector is implemented by the student as part of an alternative model making use of techniques from scattering theory. The implementation is done in the framework of a fitter written in CUDA designed to run on a GPU.