VecAmpFit: vectorized amplitude-analysis fitting library

Abstract

A new library VecAmpFit for multidimensional amplitude analyses in high-energy physics has been developed for an ongoing amplitude analysis at Belle II experiment. It includes a fitter performing likelihood calculation and explicitly-vectorized subprograms for amplitude implementation. The fitter supports explicit gradient calculation and simultaneous fitting of multiple data sets.

Figures (9)

• Figure 1: Results of fit to the $D^0 \to K^- \pi^+ \pi^0$ signal distribution for a pseudoexperiment. The points with error bars are data, the solid line is the fit result, and the hatched histograms are the background contribution.
• Figure 2: Projections of efficiency fit results onto $M_{K^{(1)} \bar{K}^{(2)}}$, $M_{K^{(1)} \pi^{(2)}}$, and $M_{\pi^{(1)} \pi^{(2)}}$ for the energy point $\sqrt{s} = 2000\ \mathrm{MeV}$. The points with error bars are efficiency (fraction of reconstructed MC events) and the solid line is the fit result.
• Figure 3: Resolution in $M_{K^{(1)} \bar{K}^{(2)}}$, $M_{\pi^{(1)} \pi^{(2)}}$, and $\theta_{\phi_J}^{(5)}$ for the energy point $\sqrt{s} = 2000\ \mathrm{MeV}$. The points with error bars are resolution (difference between reconstructed and generator-level value) and the solid line is the fit result.
• Figure 4: Projections of background fit results onto $M_{K^{(1)} \pi^{(2)}}$, $M_{\pi^{(1)} \pi^{(2)}}$, and $M_{K^{(1)} \pi^{(1)} \pi^{(2)}}$ for the energy point $\sqrt{s} = 2000\ \mathrm{MeV}$. The points with error bars are data and the solid line is the fit result.
• Figure 5: Projections of signal fit results onto $M_{K^{(1)} \pi^{(2)}}$, $M_{\pi^{(1)} \pi^{(2)}}$, and $M_{K^{(1)} \pi^{(1)} \pi^{(2)}}$ for the energy point $\sqrt{s} = 2000\ \mathrm{MeV}$. The points with error bars are pseudo-data, the solid line is the fit result, and the dashed histogram is the background contribution.