Amplitude analysis of four-body decays using a massively-parallel fitting framework

Abstract

The GooFit Framework is designed to perform maximum-likelihood fits for arbitrary functions on various parallel back ends, for example a GPU. We present an extension to GooFit which adds the functionality to perform time-dependent amplitude analyses of pseudoscalar mesons decaying into four pseudoscalar final states. Benchmarks of this functionality show a significant performance increase when utilizing a GPU compared to a CPU. Furthermore, this extension is employed to study the sensitivity on the $D^0-{\bar{D}}^0$ mixing parameters $x$ and $y$ in a time-dependent amplitude analysis of the decay $D^0\to K^{+}\ddot{I}{€}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{-}$. Studying a sample of 50 000 events and setting the central values to the world average of $x=(0.49\pm 0.15)\%$ and $y=(0.61\pm 0.08)\%$, the statistical sensitivities of $x$ and $y$ are determined to be $\ddot{I}ƒ(x)=0.019\%$ and $\ddot{I}ƒ(y)=0.019\%$.

Proceedings of the 22nd International Conference on Computing in High Energy and Nuclear Physics, CHEP 2016